Good job calling out how poor or misguided workmanship and lack of understanding of the building science leads to poor outcomes. I'm glad you're doing this work to help builders make fewer mistakes, less waste and better performing homes.
Unfortunately, especially in spec houses there is quite a bit of poor and/or misguided workmanship. The risk is that a significant number of bad spray foam installs (particularly in climates that are very cold or very humid) will give the rest a poor reputation and cause increasing difficulty in getting insurance or mortgages. In practical terms the perception can be as much of a problem as the reality.
@@benz-share9058I want to reiterate this. For all this to work four contractors need to know what they are doing with spray foam. Being on job sites where the trades are out back smoking pot and basically putting the minimum effort into their work, where the subcontractor himself only shows up every other day to inspect his workman’s work . . . .this in Houston aint gonna work out well. We have far less sophisticated systems that essentially. The framing contractors, the decking contractor, the foam applicator, the attic ventilation system, the roof deck and roofer. Matt even made a video on how this foam collects moisture at the peak, you got to know what you are doing to prevent it.
I'v been seeing this sort of nonsense since I used to read my dad's builder's magazines in the 1960s. Maybe I'm being a hard a* but the moisture issue seems pretty obvious. You don't use open cell foam anywhere near water- unless you're washing dishes with it. Who are the engineers who signed off on this? They should all lose their licenses. The companies, especially the principals of those companies should be paying to remove this stuff. A large French boat builder known for cutting corners on structure (weak thin plywood bulkheads, also absorbent), uses open cell foam for deck structure, gluing the frames onto hulls. (Would you glue or bolt a house to the floor deck? ) The decks after several years rot and fall apart. My boat has a closed cell foam core for the deck. It's effectively permanent. meaning my boat will last 100 years at least.
Where do you find a company to do the job right they all cut corners and they use this crap because it is cheap. They never should have licensed this cheap crap in the first place.
I'm in Scotland, which is part of the UK, and we've recently put Kingspan between our rafters with an air gap so moisture can escape and not rot the wood. The issue is really as your second point - older houses here have no vapour barrier in the roof so small amounts of moisture do make it through. Spray foam here was frequently put in by dodgy firms looking to make a quick buck, and they would just fill the space in the rafters, which will trap moisture as the cold air hits the warmer air of the foam and condensates, rotting the roof at the condensation line.
He thinks he has to mind US Scotland is Part of the UK Thinking Americans Don't Know Geography... Hey, Bra, Americans fully known Scotland is Part of the UK, and of Course this Red, White, and Blue Bloodied American Ross knows Ross-shire was the Old Heart and Blood of the Highlands! But do you know the 1st Official Ross a name once Protected by Law Across the Empire, the Chief of the Great Clan Ross the 4th Earl of Ross Hugh Ross signed the Declaration of Arbroath a Percussor to the Declaration of Independence, and his daughter became Queen Consort of Scotland to the 1st Stewart King, starting a War for the Next Generation for the affront to Ross that was and the affront to come from such. Hugh Ross is the Ancestor to the Majority of Ross' in the Western World, and it was Betsy Ross' Uncle in Law Col. George Ross who was last to Sign the Declaration of Independence by Date. I bet you don't even know the Last Sea, is the Ross Sea, and Yet You Doubt Americans Geography Skillz!
I used to use a lot of spray foam. Then we did a reno on a house that had what should have been a pretty minor roof leak, but because the foam trapped the moisture between sheathing and the foam it turned into a catastrophic amount of damage. There are still situations where it is almost a must, but we use it sparingly.
This is the problem with closed cell insulation, you don't see a roof leak. So, open cell allows condensation to rot the roof, while closed cell allows a roof leak to accumulate moisture. Insulation above the roof helps keep the wood from being cold enough to condense. Open cell below it helps a roof leak to be visible instead of rotting the structure. There are roofers in the US who won't repair a roof with spray foam below the roof line.
Imagine the cost when someone needs to remove all that spray foam. Its literally going to be gluing everything together and blocking any visibility to water damage starting in the wood.
Here in Norway we basically don't use any spray foam. It's seens as toxic, worse when it comes to fire and higher risk for water damage. I think all of the Scandinavia is the same
Here in Finland I use cellulose insulation in the roof of my log house, and no vapor barrier - only a permeable air barrier. No issues with moisture build-up and easy to check for potential problems.
Hi from the UK, the UK gov has a history of 'insulation' programs that are used as ways to make jobs. A lot of people who dont have skills end up with low paid jobs insulating houses, there are good people doing it but there's also a bunch that pop up just to sock up the government money before the deadline ends. It always ends up with a lot of problems, it's a rush to get the grant money over a real care for the work.
We have the same situation here in the USA. The government has weatherization programs that are largely staffed by unskilled workers that are poorly trained and have no basic understanding of physics. These weatherization programs often lead to homes having mold, moisture and IAQ problems.
It’s also a UK class E combustible, (not great) Polyurethane spray foam is nasty noxious foams at higher temperatures. Anyone who installed as part of any insulation program, should be up for fraud and anyone who has this in are rented properties loft and not ripping it out should be up for corporate manslaughter if the property does a Grenfell.
Howdy from a Texan ex-roofer (with young knees LOL) that lives in France but previously all over Europe/ME. First problem is that Roofs are NOT built like in the USA ... where we install plywood/OSB over the trusses and then apply a tar paper layer before asphalt shingles. Here it is def "open air" with clay tiles resting on batons and nothing but the wild blue yonder between. Throw in high winds (especially in the Athens area of Greece where I even lost tiles in high winds) in rainy conditions and you've got a "colander" type roof; your reference to 1x4" might be typical in the UK but nowhere else. Also keep in mind the Trusses rest on cinderblock or concrete wall structures; in Israel, the roofs are solid concrete in some cases ... sort of required in a Country where EVERY house/apt must have a "Mamad" or bomb shelter of high KSI reinforced concrete and it ain't just "rain" coming down like now. On a side note, Hurricanes and Tornados don't really cause much damage and the USA should learn from this construction method ... not much more expensive for new builds but would require a re-train of our crews ... much different approach. Anyway, I'm with the Insurance Companies on this one ... if the roof isn't sealed, rain/dew will certainly shorten the life span of the trusses/timbers as the spray foam is on the wrong side of the equation (trapped) ... "black mold" is worldwide BTW. So on a retrofit, clay tiles need to be remove, plywood/OSB installed and tar paper laid before reinstall of baton/tiles. "Governments" ??? What are ya gonna do??? Same ones that allowed "Lead" to be added to our Gasoline back in the 1920's just to quieten down valve trains ... not well thought out. We'll see how Solar Panels fare. Cheers.
Very informative comment, thank you. I've seen a few videos in the past about concrete homes and wondered why they weren't more popular. Seems like they would do better in severe weather. I'm not a builder, just curious.
As I see it, the issue is ventilation. Provide adequate roof ventilation, and this should be a non issue. I don't think it has anything to do with using osb sheathing. And almost nobody is using "tar paper" anymore... nobody who builds quality anyway.
@@TimTimTomTomI just took the tar paper off my 100 year old house and it was in great shape. Replaced it with more tar paper. I'm not convinced tar paper isn't quality. 🤷🏻♀️
@@TimTimTomTom ... and you live where? Want to nit pick over tar paper vs plastic wrap or plywood over GP water resistant sheathing ... everybody's got their opinion. But my point was neither is used traditionally in the UK or EU ... and when the wind/rain is coming at the roof horizontally, all that water will be trapped in the foam barrier instead and initiate rot; the reason for the content creator's post.
Let's be clear about "tar paper". I am 70, worked in construction before retiring. I have seen very few houses with actual "tar paper", and those were old houses. Newer construction ( most of my lifetime) uses "felt", which a lot of people confuse with tar paper. I had my own roof replaced in 2014 and they stripped and reinstalled 30 lb. felt, before laying the fiberglass shingles. Not putting the felt is kind of foolish in my mind as it insulates ( however slightly ) and provides additional barrier to water penetration should any get through the roofing.
Matt, here along the Gulf Coast in the US, non-native Formosan Termites are causing a LOT of problems. And the closer to the water you live the worse it is. Recently, I wanted to upgrade the insulation in our attic from fiberglass bats to spray foam. But I quickly found out that our termite company (Terminix) would drop us (cancel the bond) if we installed spray foam - for fear of trapped moisture which would in turn attract termites. Called other pest control companies and they said the same thing. Talk to your builder buddies in Houston about this. It is a BIG deal along the coast as every single home on or near the water has had a Formosan termite infestation. The Formosan termite colonies are an order of magnitude larger than normal subterranean termites and so they eat a lot of wood in a short time.
I've never seen any insects in foam. I have seen it in every other type of bat insulation. They love to nest in that stuff and once it gets wet it never drys out.
I agree with you and like your comment. Question: Are you also a bit older? I only say that because I have been a building contractor for about four decades and have seen many products not hold out as represented. A popular product "PEX"warranties 25 years, copper 50 years. 25 years is not very long buried in a wall of your home.
Absolutely correct. I live in an 80+ year old home and have been able to renovate and repair much of it because it’s all accessible ( water damaged fiberglass insulation, insulation in the wrong places, leaking pipes, substandard electrical wiring, etc.). If any of this was inaccessible, we’d be looking at a demolition and rebuild. Radiant heating embedded in concrete? You are putting a lot of trust in something that will be a nightmare to fix if it fails.
@@fsoileau I respectfully disagree with your Plumbing analogy. We don’t know the lifespan of PEX yet. Just because the warranty is set for 25 years doesn’t mean it’s not good for longer. We’ve all seen copper lines that are well over 50 years and are perfectly fine.
I have seen copper lines that were installed touching a dissimilar metal and have corrosion to the point of failure. It comes down to how it is installed same as PEX
You have missed the point why the mortgage companies are unwilling to lend on spray foam insulated houses, while doing a great job of explaining the science. The issue is that the roofs with spray foam are hard to inspect for issues (especially caused by damp) and together with a significant number of poor installations this has led mortgage lenders to refuse to deal with spray foam. The idea of mortgage lenders or insurance excluding certain categories because they are awkward to deal with is certainly something that happens in the US, too. It doesn’t have to be spray foam insulation.
The next problem is most of these houses have to pass a blower door test when they test for air tightness, the regulations are getting tighter. I’m seeing some builders not pass the DET(duct envelope tightness) test because they didn’t spray foam. If states want their houses to get tighter without spray foam….a lot of builders arnt going to get their certificate of occupancy. It’ll be the builder apocalypse
Properly installed closed-cell foam can be a real boost for increasing the durability, comfort, and energy efficiency of the housing stock. Eliminating that option by refusing to insure it, is a bad move _in the long run._ In the short run it makes sense from the insurers' point of view, for the reasons you stated. What needs to happen is that the UK government needs to have more demanding education and training for insulation contractors, so that they know the right way to do things. This applies to building inspectors as well. With the contractors properly trained and regulated, the building failures won't happen and the insurers will be able to take on an appropriate risk level.
@@MrDbraultwhat is their issue with PEX? the only issue with PEX is not installing the fittings correctly. Assuming the job was done right, it's good for a hundred years.
English carpenter and gc, now living in VT, USA. Spary foam was and often still is sprayed directly to the underside of roofs in older houses which are more often than not tiled in slate. The foam is sprayed to the back side of the slate. condensate forms on the rear of the slste, and air flow is now restricted meaning the moisture has no where to go and so rots the timber frame roof, that supports the slate. Meaning a whole new roof needs to be cut, then slated to remediate the problem.
I think you missed the comment where she said that she had black mould prior to the install. That is very common here, and indicates that there was already a problem with condensation to start with. The high humidity here means that people don't really trust wood buildings. One of the issues was the way that the grants were structured - it encouraged companies to quickly do a lot of installations with minimal / no training of the staff, and no consequences if something went wrong. So it did not matter to them whether or not the roof rotted afterwards.
Hi from UK. Really interested to see this video Matt. Our Health & Safety Executive (HSE) have just issued a report on spray foam (no idea why as there is no H&S implication). They say that the risk of rot varies according to roof construction, type of foam and and climate, but if done properly is not a problem. Open cell seems to be preferred here, theory is so that moisture from below can pass through newer style breathable membrane as opposed to traditional impervious bitumen underfelt plus double height roof battens to ventilate under the slate / tile.roof. The HSE also advise open cell. Nothing is said about thickness or whether rafters should be covered..Vapour barriers unclear. Its just a mess. I read that just one senior surveyor set this hare running, as he came across a couple of rotten roofs, and now everyone is running scared. The standard foam thickess used here is only about 4". There is a bad history of closed cell being applied directly onto the underside of tiled or slated old roofs to "hold it all together" to keep the roof going past its life. Thats not good. Cowboy operators bolstered by well-meaning government grants, have applied the wrong foam in the wrong sort of roof in the incorrect way, and badly. Building techniques in UK have been changing, warm roofs are now a thing but that is fairly new. The more common traditional cold roofs need lots of through ventilation, with only 300mm rockwool type insulation on the loft floor. Lots of strong anti-foam opinion over here!
That lines up with so many stories I have heard from England on buildings. The regulators are extremely slow to address new tech, and by the time they do there are huge issues. And very aggressive opinions on it. Like your comment on closed foam, it is great stuff if used correctly and not to cover up structural or other issues like you pointed out. So now closed has a bad rep because of it.
@@darkshardrex7589 UK doesn't do prescriptive design codes. It's very subjective with objectives you should produce. And as the Grenfell Tower Fire showed, there are a lot of people in the UK confidently doing design and construction very wrong. who are overseen by inspectors who apparently have no idea what they are doing and standards bodies in the pocket of manufacturers.
The problem I have encountered repeatedly in the US is that finding a good installer is incredibly difficult. It’s hard to know if people are doing things correctly unless you yourself are an expert. Had a mini split install recently where contractor made a subtle mistake welding (edit: not welding, brazing) the line set and this caused thousands of dollars in damage to the cassettes. The install LOOKS great. Inspector didn’t think to ask about it. My concern is that mortgage brokers and insurance may lump everyone together and cause problems for modern homes no matter if Matt built it or not.
I just made a comment about the lumping together. Big companies seem to do this quicker. Might have to seek smaller insurance co's to get coverage. Good to still be able to get coverage but limiting options isn't great.
Let's be honest. In some areas of the construction industry in the US far more than half of the workers aren't even supposed to be in the country in the first place. Of course they're going to take any and every shortcut available to them. Most of them don't even get paid per hour but get paid for job so the goal would be to do whatever you're doing is fast as possible.
@JustNo8808 You know what, l can be honest too. I've worked with a bunch of these guys over the years - talking about construction workers you pick up at home depot or wherever for day labor - work by the hour, get paid in cash at day's end. I don't know that they were all undocumented but no surprise if they were. The point is, they frikkin work. I'm sure there's exceptions but the guys I've worked with were friendly, respectful, focused, followed instructions, asked when unsure, and strived to do the work as expected. We'd get their numbers and call them back whenever needed for more projects. They were cheaper and better than calling some established subcontracting company that might get to you the Tuesday after next and then be delayed, and when finally on site do things their way instead of how we wanted it done. Americans literally did this to themselves; I'll take hispanos all day long! (That doesn't mean I'm for illegal immigration; I'm not. I'm for LEGAL immigration and carefully vetting everyone allowed to immigrate. I'm looking forward to the incoming administration sorting out the mess of the outgoing admin)
Open or closed is bad for roofs. Issue is that if the roof has a leak, its make be impossible or very difficult to locate it. Water will pool & rot the roof. Either batts or cut peices of rigid foam panels should be used instead. You can always remove them for inspector or roof repair. I suspect in the next 3 to 7 years there are going to be a lot of US homes that need roof replacement caused by spray foam.
I live in South Florida and I have had to do WDO inspections for home refinance. There has been issues with homeowners Who have put in spray foam insulation and cannot get bank approval. For the most common reason of it, making it inaccessible to see if there is or was termite damage that's being hidden/ iconcealed by the insulation. It also prevent us from being able to treat the exposed wood throughout the attic in a preventive fashion against wood destroying organisms using profucts like bora-care or premise2.
As a UK PassivHaus architect and project manager, I applaud your channel. I have been advocating that we need to build more like Americans here and move rapidly away from the so called traditional methods favoured by UK contractors.
I would strongly disagree with you, from experience of being from the UK and having family in the USA we should not be copying them. We have historical and economic reasons not to build in timber as the supply is not local and costly in comparison to the USA. Matt also references Dr Joe Lstiburek constantly, and rightly so. If you watch his lectures on the perfect wall or the institutional wall which will last and provide good performance for centuries then he basically describes the UKs standard brick and block cavity wall used in most houses today. Architecture jumping on the latest fad, like timber frame construction also cause reactions in regulations like the new part O, or overheating. Ignoring the fact that it contradicts part k and m for window guarding, the elephant in the room is no consideration is given to thermal mass in any of the calculations required for building control. This is not the case in Germany for example and makes light frame construction look great on paper but it's an illusion. The USA are heavy users of aircon, but with thermal mass it just isn't required especially in the UK where problematic hotter weather only lasts for a few weeks at most. The Romans knew it, the Greeks did, they still use it in the middle East and some parts of Australia now. A couple of years ago with 34c outside my living room 1910 cavity wall direct lime plaster on engineering brick with 150mm natural yorkstone exterior with a 30mm cavity didn't rise above 22c as tracked by digital thermometer and humidity sensors. My mostly timber framed well insulated room in the roof however didn't drop below 30c My point is copying someone else's homework for English literature may not help you in a French class if you get my meaning. The UK and USA have different resources and climate conditions, resources and physics dictate what will work economically not fashion.
@@colinmendelowitz249 no brick has nothing to do with it. In fact a lot of the house builders are looking to go timber frame as that's cheaper! The performance though is inferior in most ways other than speed of build and possibly air tightness but that's debatable.
@@nathanlegge7090 Thermal mass is indeed a good thing, but it's also usually very high-carbon. There is a tension there. It can be offset by very long lifetimes. Passivehouse says nothing about timber vs brick vs concrete vs whatever - it's all about building physics that adds up. And it removes any issues with condensation in the wrong places, and makes very comfortable houses with tiny heating loads, that don't overheat. The art is building good houses without an epic up-front carbon cost. Less brick and concrete generally helps with that, but stone can be very low-carbon if it's not had to come too far.
While properly installed closed cell insulation with no leaks will solve the problems from vapor condensation, It can greatly increase the risks from bulk water from above when the roof fails. Yes, some people replace the roof when a periodic roof inspection indicates that the roof is close to end of life, many people first thought of roof replacement is when the brown stain in the ceiling gets larger and may take a year or more to figure out how to pay for it when they get an estimate of the cost. By that time, it won't just need a few pieces of roof sheathing replaced, it will need much more sheathing which is still glued to the insulation where it hasn't rotted to mulch and roof rafters with it. Won't it be fun to rebuild those trusses. Much of this damage will be done before any water gets through the closed cell foam to leave the brown stain on the ceiling.
Having lived in the UK for over a decade, coming from continental Northern Europe, the type and quality of construction in the UK is shocking. It’s not only the cold climate, it’s the year-round humidity, and that they absolutely weren’t building for it. Your comment that some house are “under-insulated” made me choke. There are buildings here as recent as 40 years old that have either 2-3 brick thick solid walls, or a 2 brick thick wall with a totally empty cavity in between. No underfloor insulation, no roof insulation, just the expectation of cheap natural gas for all eternity. To the point that the only way to adequately dry out your house is to have heating on 24/7. The spray foam roof insulation ‘scandal’ is the result of an endemic culture of short-sightedness coming home to roost, not only once (when originally built), but twice (when foam was installed). New requirements here finally got higher air tightness and requirements for mechanical ventilation (ERV/MVHR), but even then the homeowner rarely understands what it’s for, what it does or how it’s supposed to work… much less maintains it properly.
I believe you were underestimating the average relative humidity in the UK. In addition to that due to the high relative humidity outside, there’s going to be a certain amount of water vapor that penetrates the roof and is then trapped between the foam and the roofing material. When the temperature drops there’s not time for the moisture. to escape, and consequently will condense.
Matt, most of the pre 1920 properties in England are slate or clay tile fixed on timber (lumber) battens fixed directly to the top of the rafters with no underlay, roofs then started to include a layer of roofing felt below the battens with this becoming the norm from about 1950. The use of timber sarking boarding above the rafters was generally only used on higher quality/status buildings, it has only become more common on domestic building recently, especially where there is habitable accommodation within the roof space. Spray foam only really began to be used in England from the 1980's and then generally only for retro fitting, its use mushroomed about 20 years ago when there were government grants available for installing insulation to older properties, this attracted many unscrupulous installers with little building science knowledge to promote it for totally inappropriate situations who then often had very poor inhalation procedures.
Hi Matt, UK roofs typically for the age you are talking about and even modern builds are felt underlayment, battens and terracotta tiles, plywood sheeting is not normally used. The loft spaces are built as cold roof, modern (last 30 years) will have ridge and soffit vents.
I put a layer of ridged foam between the decking and spray foam. If the decking needs replaced we should be able to peal the bad decking off without touching the spray foam. Time will tell though
I'm from the UK and the house I'm in had this. The survey report was basically what you said, so nice analysis there. In the end I offered the seller £20k less because of this and I had all roof tiles replaces which was quite a big job.
That house looks more like 90-100 years old rather than 40. Roof structures in UK are generally very different to US. "Under insulated" is an understatement. Recommended ceiling insulation in UK is 300mm (12"). Normal is fibreglass. Tiled rooves on tar paper with battens is normal and as you say relatively breathable. Your homes in the US are very different.
There was also an episode of Holmes on Homes, or another Mike Holmes show I believe where they removed everything due to the spray foam installer spraying the foam too thick up in the attic, thus it would never fully cure and was slowly constantly outgassing, which was making everyone in the home sick.
@@stephenmitchell4393Technically correct, but could be misunderstood. So people understand - this has nothing to do with how many inches are applied in total. The problem arises when the applicator moves too slowly or over the same spot too many times before the foam can cure. Uncured product can get trapped behind cured foam and stay that way. It usually smells horrible, and therefore isn’t a danger because it’s caught.
@@nunyabidness3075 Right, as there is a difference between spraying 1 thick application, or spraying multiple thinner applications to create the same thickness.
A popular phrase I've heard: Seal tight Ventilate right Yep we seal these up so much that the fresh air that used to permeate the envelope needs to be introduced mechanically.
The general public don't understand how important it is, but professionals for the most part do. Build tight ventilate right is a good catch phrase but you have to know the likely failure modes and mitigate them. Older designs have had hundreds of years of evolution to be perfected with local adaptations used for local climates. Foam insulation, chipboard, osb and to a lesser extent plastics are getting that evolution now and it's proving some to be not up to the task or causing secondary issues. Construction is quite conservative in it's approach for good reasons as the consequence of failure can be very expensive
I kinda have this debate often with people online. Spray foam is fine but you need to do a bunch of work first to make it acceptable, it’s best on new construction.
Chatgpt can be very accurate if you ask it questions the right way. The best way I have seen it explained is talk to it like you are walking up to a random person that knows everything to ask them a question. If you give some vague question it will get confused. If you give it a very detailed question it will be accurate. I also never do what is called zero shot prompting where I try to get an answer immediately. I'll tell it what I'm trying to accomplish and get it to first explain the process it should take to get an answer and I'll usually also give it a role to play. Once it gives me that information I'll tell it to start to work through the problem. Especially with the new models they have it will spend a lot of time working through the problem. The funniest thing I did was I figured out a bunch of different "experts" that would provide good input and once each of them gave me an answer I asked them to have a meeting. It took a while to get the answer but the output was funny because it literally was a meeting where they ended up having meeting minutes and I could see them actually debating each other and correcting any issues they had missed. The output was 61 pages long.
@hotshot619 Yes, thank you for saying something. It drives me crazy the way people have come to just reflexively trust the Elaborate Lie Machine. It's designed to spit out sequences of words based on probability--it's not an actual, thinking researcher that can understand what it's saying.
I agree in the sentence that cgdp is a bad source of info , better search for info and go to Links that is presented and sheck the quality of that info . Whether stats in the uk : go to there whether afforety.
Great video! Thank you for making sense of this otherwise click-bate headline. I'm glad people like you are willing to do the work of what the old media used to do.
@rsmith02 The extention the house, block all the ventilation, build a roof over a roof... a total of seven layers of shingles on over the others on a 2/12 pitch... And they use spray foam to hides everything
I've seen someone do a fire test on that spray foam and I've gotta say that in a fire it actually boosts the flammability of the house. See the heat melts it and it just turns into oil which burns hot and helps keep the fire going and spread.
Good video, the conclusions are good. You are low balling the humidity in the UK. Depending on time of year and location it can vary between 50% to 90%. Most roof construction is roofing felt on top of the rafters you see in the videos with batten nailed on top of that to hang the tiles from (tiles are nailed as required by building regulations) so not a lot between the cold tile and the inside of the roof space, nothing you would recognise as a deck. The big problem with this sort of work is the government grants for it. Companies will convince people that the the new (funded) thing is good for them and do the work, then get paid by the government irrespective of whether or not the house is suitable for the work or not. This behaviour repeats with each new government initiative to improve the (elderly) housing stock of the country.
America needs to establish serious trade schools that specialize only in residential home construction. Offer a graded certificate for proper completion of the required course load. Homes are too expensive to have knuckleheads being taught by other knuckleheads at homeowners expense. In my opinion knowledgeable craftsmen are in short supply.
Yes or more in the attic. But also the ventilation at the rafters is missing in many of these situations, so there is often no path for the moisture to be removed.
Regarding roof tiles, having lived in a 2005 built property, the truss was covered in a sheet of membrane (plastic), then 1*2 battons and then concrete tile. This was very very common by builders such as Persimmon, Bovis, Crest etc etc
I wouldn’t have thought that the humidity in a typical UK home would be anywhere near 35%. Do most UK homes use forced air heating that would lower humidity. The weather in the UK is typically humid and the weather is typically rainy almost like Seattle.
Cheers from Canada. Been a guy who has built 2 - R2000 homes - 20yrs before they were adopted. Working on a NET ZERO. heavy insulation wall and ceiling, Double 1980 standards. It was a response by NBPOWER executives to the 73 OPEC crisis . Our area - is - 50 F. We need to release water - and decrease moisture into the house. For years - I have used - forced air movement. Thank you MATT - cheers!
The predominant feature of UK climate (not that we have 'climate', we have weather) is the damp. Relatively high cold temperatures feel bitterly cold due to the humidity. We have a saying : too cold to snow. This comes from the times it gets really cold is when there aren't any clouds.
Sure, just ignore the squirrels running around and pooping everywhere, and ignore freezing your ass off in winter or paying $400/mo in summer to air condition the place. Ventilated attics are OUTDOOR SPACES.
@@Crusader1815if you do insulated rafters with narrow outdoor venitilated slits under the roof boards ( like 2") you can have full room height, and get a nice" non boxlike" room volume.
Love watching your content being in the UK its really interesting how in some ways your are ahead of us and others we are ahead of you. . That house your talked about was likely built in the late 60s-70's. That vertical "waterfall tile" on the 2nd story was popular then. Houses into the early 90's were usually built with rafters and later trussed roofs were utilised. So your correct that they are typically thicker timber than a truss roof construction. The major difference in roof construction though is the UK uses unconditioned roof spaces versus the usual conditioned roof in the USA. Most construction I have seen on your channel for the USA uses OSB, ZIP or similar as part of the external roof substrate. UK houses of that era, unless they have been re-roofed (which is not typical, roofs in the UK will often last upto 70 years+) used a bitumen/felt underlayment installed underneath the roof tiles (modern construction now uses the same materials I see in the USA, depending on roof construction requirements). So when you only spray foam insulation inside the roof you impact the ventilation characteristics which generally results in condensation leading to wood rot. . The more appropriate method of retroactively insulating the roof itself would be to install a small spacer, say 15-25mm around the edge of the rafter space (creating and allowing an air gap between the roof underlayment and the PIR - exactly like you have on your wall siding) and then cut 75-150 PIR foam insulation to the size and use Gapo Tape or Sealing Tape around the edges. This allows for greater insulation values to be installed in the roof whilst maintaining the necessary roof ventilation. . The reason that this has become a problem is twofold: Originally it was one of several approved retroactive insulation methods that met the requirements of the "Warm Home Initiative Grant Scheme" set out by the UK Government to reduce heating costs for the lowest income households and the worst performant housing stock in the UK. The second is that whenever UK goverment funded schemes are setup there is a mad rush by lots of unscrupulous companies to cash in. This led to many "cowboy builders" spraying foam insulation without any care or consideration of the reason that properties were built the way the were. . This is still the case now with the UK's push to Net Zero and increased emphasis on Air Source Heat Pumps. Currently we have a £7,500 grant available when an ASHP is installed and a Gas Boiler removed. In the very early days this was pretty much only taken advantage of by high income households. It should have always been a "means tested" grant ensuring that those with the least money and typically highest heating costs benefited the most. When you consider that a Gas Boiler replacement can be typically carried out for £2000 or less (mostly just a replacement unit) but the average cost of installing a Air Source Heat Pump is £10,000-£15,000. This is due to the different requirements in convection radiators at lower temperatures: Gas Boilers run 70'C Flow/50'C Return historically - current standard is now 50'C Flow/30'C Return versus Air Source Heat Pumps anywhere from 35-46'C Flow/30-41'C Return and heating pipework from the ASHP need to be larger due to the increased flow rate (Heat Pump flow rate is 4 times a Gas Boiler). . Up until sometime around the 2000's we used to have local government employed building inspectors but in an effort to reduce expenditure by the Conservative governments and to decrease "red tape" and increase the numbers of house building a large proportion of the building inspectors were made redundant and the responsibility conferred to the house builders themselves. So they now employ the building inspectors themselves. Even though building standards have increased there is obviously a conflict of interest between the enforcing the building standards and keeping build costs low. Typically you find that the "good building inspectors" who enforce the standards rigidly are not employed for long by the house builders in favor of those with more lax standards....! . We also have a situation where houses that have flooded or are built on flood plains are no longer insurable for flood damage once the Government backed insurance initiative ends in 2039 www.floodre.co.uk/about-us/
Spray foam doesn't work well in homes built 100+ years ago, because the home was literally built to breathe to dry out. It is a very different concept that we have today. Air flow in walls used to be encouraged, so that you wouldn't have mold. The issue is that this was a fire hazard as well. If you take a balloon wall construction from the 1800s and the roof framing that comes with that, and you button everything up with open cell foam, you will get condensation on the wood and eventually it will rot.
2 inches of closed cell foam then I went across the studs with aluminum double bubble and then taped it all off. 12 years ago. No problems. I did not close up the attic. it was vented and had 2 windows. Cut my heating bill by 80%. needed a/c 2 weeks out of the year. Never saw a bug ever again. Never heard my neighbors ever again.
Retrofitting can certainly be done, but the whole thing has to be re-done. Pull the shingles off, clean it of any mold, replace rotted boards, then use a modern water/air barrier. None of those skip sheathing boards either. Seal it up, then use enough closed cell foam to overcome dewpoints, and have it properly installed. Roofs and walls are systems, and the components of systems must be engineered to work together.
@@pb7379-j2kI completely disagree with you. A hundred years ago and more people took pride in their work. They used locally sourced materials that were cheap and very sturdy. They heated with wood that created more than enough heat to cook and stay warm regardless of how cold and windy it got.
@@Ed-ym4tu Yes, I'm sure they were master craftsmen with no question the best quality materials. The wind that whistles through the walls of old houses was on purpose I'm sure LOL
FYI, the UK is relatively humid. Expect roughly 60% humidity indoors even with some use of a dehumidifier, and 80-95% humidity in an uninsulated loft. Even without spray foam involved, it's very common to have condensation issues if additional ceiling level insulation is added, cooling the loft. Middle-aged housing stock (say 1970s) has non-breathable bituminous sarking felt under the tiles and typically relies on gaps at the eaves for air-flow - which may be blocked by extra insulation or boarding laid down for storage. Without adding felt lap vents or ridge vents, it'll be raining inside just from warm moist air leaking into the loft and condensing. Makes it easy to see why spray foam would be an issue. You're still getting warm moist air escaping into the loft, but now it's condensing right at the rafters with no ventilation to dry it out, migrating through the foam as you say. And if you encapsulate the rafters, no-one can inspect to see if any water is getting through the tiles - so neither open-cell nor closed-cell foam is really acceptable for a retrofit.
I agree with the humidity, as a Brit who moved to Massachusetts it is incomparable. 60-70% compared to 30-35%. Also the weather, it pretty much rains or is damp every day in the UK from November to March. In Massachusetts in December to February it is super cold but dry. Another thing is Brits tend to air dry their clothes in their house, Americans just use a dryer as electricity is so cheap, like 1/2 the price.
I saw this news when it came out and remember thinking, this should be no surprise. When so much has to be perfect, along with installation, then that's just nuts to put your faith in that many unknowns. Better to keep things simple that can be repaired easily. My house is a medium size that i took certain precautions with when i built it and i would never want my roof deck insulated. My house is very comfortable and not drafty and my heat pump can condition the house in a hard winter in the south for $80/90 mo which is excellent and summer AC is only $60 when i observe peak hours. So insulate but keep it simple and don't fall for a lot of hype from those who want to sell some grand vision of miraculous products that are going to let you heat your home with a candle. You could wind up with rotting and unbreathable, nasty homes. I don't want to be tied into the systems any more than necessary and means avoiding repairs in a super rich labor environment.
The issue is spray foam is being used to cover up structural issues and mold. It can also trap moisture. Nearly all homes in Europe are 1970's or earlier built.
Another comment regarding moisture control: It’s my position that you will never be able to completely keep moisture out. Even if you did, I’m convinced the seal would fail over time. A “tight” house is a trap for moisture. Instead, I focus on what I call “moisture management.” I assume moisture will get in - so I make sure there’s a Way for the moisture to get out. For example, I advocate installing siding with a small gap between the siding and the moisture barrier. That way, any moisture that gets in can drain out. I ensure there’s a clear air path on the underside of the roof, from attic vents to ridge vent.
Good on you Matt for doing a deeper dive on the story. One of the ills that has grown out of the digital landscape is a tendency to take in a headline and little else. Throw in the obligatory shock factor built in to the headline to encourage clicks, and it makes the "drive-by takeaway" that much worse.
This reminds me of a video you released about 3 years titled "I’m recommending we NOT INSULATE This Old House" The historical context and designs used on these old english homes is not being taken into consideration when adding insulation. They could even have these issues with normal rockwool or fiberglass insulation if installed in the same way.
My parents' home, built in the 80s, has spray foam under the roof BUT sheets of rigid foam were tacked up underneath, leaving a 1-inch gap between the roofing material and the sheet. Foam was then applied to the outside of the sheet, allowing air to flow under the roof from the eaves. Never apply foam directly to the plywood or whatever the underside of the roof is made of.
Before I watch the rest (I'm only 2 seconds into the interview), Im going to veture a guess that (like everything else HVAC related in GB) they are doing it wrong; Government subsidies caused a bunch of businesses to spring up overnight without proper understanding, training or expertise and a whole lot of salesmanship (backed by government messaging). Now back to it, let's t see how my prediction holds up.
I concur. We had our city mandate on homeowners to put water pressure regulator. They said that if we do it within two months, we can get reimbursement, but if we don't, later on we will have to foot the bill. They even gave us suggestions which companies to call. After install, it needed to be inspected by the city inspector. I called and guy was send to our house in 2 days. I checked during those days about total cost and the highest price for top tier back then was $95. City stated that they will reimburse up to $850. Notice word "up to". The guy came, did it in 15min and charged us .... yes you guessed it, $850. Then magically city Inspector for which the wait time is usually over a month, showed up 2 hrs after job was done. We both went into crawl space and thank God he came so fast (although I found out later that they scratching each other's backs). The water was dripping and since we always had bucket sitting under crawlspace water shut off valve, I had already about 1 /4 of gallon of water in a bucket. I panicked and told the Inspector that I will call the guy to get his butt back right away to fix the leaking issue and a da... Inspector tells me " don't bother him, it will be ok. In time the dirt and and grease from the surrounding area will plug up the connection and act as seal and stop the leak. I know that guy and he is always doing a great job". That's when my red flag went up. The city inspectors and other officials were directing people to their buddies because there was "free" money flying around. I told his that I don't give a crap since I paid $850 for job that took 15 min and part for $95 (they probably had further discount) and based on travel cost of the company and per Hr labor, should cost on high end even if charging 1 hr labor, no more than $550. I called the guy back. He came back ticked off. This time I watched him like a hawk and it took him less then 7 min to fix it and no leak after that. I was furious because this city reimbursement money didn't come off the tree, it came for property taxes from all of us. People who couldn't afford to pay upfront costs and be home magically waiting during the week day hour for installer, got screwed.
From the UK here, you are 100% correct. Companies springing up and taking the Government money and doing an awful job and the homeowners then have to live with the consequences. Same thing is happening here now with Heat Pumps. Company’s springing up, taking government money and doing terrible jobs leaving the homeowners living with something costing them 4x the running cost of the perfectly serviceable natural gas boiler they had ripped out in the name of being green!
@@gund89123 It does, but it's for insulation in the general sense, not specific to foam. Also, these are established industries in the states, with experience and established best practices. This is not to say that there are not shady installers making a mess of things in the states, there are, but it's not an entire sector that has just sprung up out of nowhere based on artificial incentives and promotional messaging (advertising) from government.
Great treatment on this topic... I'm originally from USA and have been living in UK for 11 years... it's horrific here in terms of damp and mold problems. The average humidity level in most homes in UK is above 60% for example, which drastically alters that dew point you spoke of so it happens much more easily. Further, even in homes using ceiling level insulation and no under roof insulation as should be done here, many of them do not have proper venting of the attic space, it's all closed in. I guess it is to be expected, the UK gov was until some point in 90's telling their citizens to vent their clothes dryers into their homes to help heat the home! After decades of doing that they then discovered the massive mold and associated health problems it was causing and stopped recommending people do that, which then became a recommendation to use condensing dryers. These are better, they do still provide a small heat boost, but they also still do put some additional humidity in the home... how much depends on the dryer and if it's condenser is being maintained properly.
I live in the UK and never heard that the government advised to vent dryers into homes. All the advice I saw was to run a vent duct outside except for condensing dryers which are relatively OK to vent into the room - but only just. The real problem in the UK is that many homes have the kettle running almost 24/7 boiling water for the copious cups of tea consumed 🤣🤣🤣🤣🤣🤣🤣🤣
I'll venture a guess that no dedicated vents were needed when the tiles were just laid on battens, but with more felt and other barriers, the codes for venting didn't keep up with the changes. Here in the USA, vented roofs have a generous soffit openings, but with vinyl siding and foam sheathing popular in colder areas, that makes it very easy for a fire to migrate from a window to the attic, destroying a house in 10 minutes.
It can be moist but it must then dry completely because mold grows in consistently moist areas only. Excellent video presentation that really got me thinking.
Matt, thanks for the video. The 2024 International Residential Code, and its predecessors, deals exactly with this issue in Section R806.5-UNVENTED ATTIC AND UNVENTED ENCLOSED RAFTER ASSEMBLIES depending on climate zone. The issue that is being overlooked a lot of times is the air-permeability of spray foam. The IRC defines "air-impermeable" (for the purpose of moisture management) as "an insulation having an air permeance equal to or less than 0.02L/s-m^2 at 75Pa pressure differential as tested in accordance with ASTM E283 or E2178." Air-impermeabilty is used by the IRC in insulation to prevent condensation on condensing surfaces as described in the video. There are open-cell foams that are air-impermeable and closed cell foams that are air-permeable. Some open cell foams are air-permeable until they are applied to a certain depth and then they become air-impermeable. The details of each foam products performance must be observed and you have to dig a bit to find it. The details are in third-party evaluation reports published by multiple agencies, the ICC-ES (International Code Council Evaluation Service) as ESR reports (google your favorite foam), Intertek CCCR-Code Compliance Research Reports or UL ER- Evaluation Reports., etc. In my office we do not use the term OPEN CELL or CLOSED CELL as it does not accurately reflect the air permeability. The key for the consumer is to KNOW what is being installed.
Great analysis, speaking from the UK. We have a history of government-incentivised unsuitable home improvement initiatives that later have to be undone. Also see cavity wall insulation and external wall insulation for examples.
Cavity wall insulation is 99% a good thing. There are a few examples of disasters, but millions of homes have been done with few problems. EWI is even more of a good thing because you have to really screw it up to cause problems. Mostly that comes from doing it on the cheap and using siliconed-on capping rather than extending rooflines, which of course practically guarantees a leak down the back eventually. You are quite right that some of the shoddiest schemes have been done under grant-funding, and we've had far too many badly-done stop-start grant schemes. That doesn't mean that govt money to improve the housing stock is a bad things, nor does it mean that cavity wall insulation and EWI are bad things. We actually need dramatically higher rates of retrofit for buildings, and the more of them that are EWI-based the better IMHO. It's usually the best technically and lowest-risk major insulation intervention. But like everything in building, the detailing and design have to be right.
A building, any building, has to be designed as a whole. Modifying it willy-nilly is asking for trouble. Taking the advice of a bunch of UK politicians is always a bad idea
I’m an engineer and I HATE the idea of spray foam insulation for entire houses. It is super hard to put fires out, it can mold easily, it constantly off gasses which reduces overtime, but is still there. Not in my house. Only as gap sealer
Matt, you are also missing a weird thing about UK homes and that is that they have water tanks in their attic. They have very low water pressure because of old pipes in the ground so they have to have water tanks in the attic to supply the house. I am sure that causes even more mosture in the attic that here in the USA.
My 1970s home has mains pressure water (about 3 bar) - hot and cold, no gravity feed. Old central heating boiler had an expansion tank in the loft but that was removed and it's now a pressurised system. That's a lot more normal than tanks in the loft these days.
Not a builder but something i’ve thought about that would help a lot of concerns is this- put an air gap. We use something near the eaves to prevent insulation from falling down there and lets the air in so why not run that from eve to ridge then spray under that? Keeps the air flow on the roof deck, so it’s cooler; doesn’t permanently adhere it to the deck making removing it and replacing it even more costly, allows leaks to escape and not sit and rot the decking. Idk if in practice if that’s good but it makes sense to me.
Insulation in the UK is generally very poor to non-existent in many houses, and I don't mean to stereotype, but most people's solution is to just put on a sweater and drink a hot cup of tea.
@@mattundercoat it is what i grew up with 😆the attic at my parents place had about 2 inches of glass wool insulation which was dong absolutely nothing. Quick trip to b&q and now they have 10 inches, and you could feel the difference immediately
I seldom see spray foam installed correctly. Most often gaps result in effectively paying thousands of dollars for nothing. Then I see deck deterioration due to moisture trapped beneath roofing and above the foam. Bring the duct inside the space and vent the attic and insulate with mineral batts.
We closed cell spray most of our projects here (Washington DC area). Never had a problem. But we subcontract it out and the installer is really excellent.
Im afraid this is a problem that applies to US too, maybe not as bad as UK but still an issue. There should never be any insulation on the warm side of any timber roof components so if your concern is heat escaping from the building you either need ceiling level insulation with plenty of ventilation in the roofspace, or all the insulation above the timber deck and none below.
Glad that the build show is addressing the diference between the UK and US on spray foam insulation. I live in London and most of our stock is Victorian then 1930 to 1970 stock. We have a very low new build rate. we had you black mould creases in the 1980 with dry rot in new build timber homes. This lead to a reduction in timber framing in the UK. Most new houses are block and brick cavity construction. on older properties, we did not have parking ( underlament to the US). As Matt points out we traditionally have on condition loft spaces.) No roof vents or poor loft ventilation. Moisture is Or was controlled by ventilation through the slate or tiled roofs. ( I am leaving out Thatched roof as that is outside of my practice area). So spraying foam between the rafter is not desirable. As it creates condensation. When roofs are recovered a marking is normally added. But is normally a bitumas membrane type. It not common to use a smart breathable membrane at this point. There is also a tendency to use the foam on roofs that have reached the end of there lifes. Which is not appropriate. Hence banks and insurers .
A guy I know works for Aqua Barrier. He showed me pictures of a crawlspace under a home that had been sprayed with foam (open or closed I don't know. Assuming open). The house had to be demolished because the sub structure had all rotted out. I'd love to use foam in future projects but can't figure out what information to trust.
The only problem with spray foam is bad installers. That's why I won't use it, because I don't trust anyone to do it right. Right mixture, right thickness, right coverage, right temperature, right amount applied in one area at a time, right dehumidiication system, right home to begin with. Most installers don't underatand half of the required variables to create a safe install.
Agreed. Installer quality seems like a major variable. However, a procedure that is easy to do wrong, and when done wrong can lead to catastrophic failure, doesn't sound like a good choice.
What if its installed correctly but then you have a small roof leak a few years down the road that goes unnoticed? Then the rot and damage will be much worse with the foam essentially holding water like a pool. Anyone living in rural areas with extra squirrels, mice, birds etc... can always have potential for a critter to make small holes looking for entry and nest areas. So many things can happen over the years. Spray foam will be costly repairs for some people.
With 30 years of experience in architectural engineering of commercial buildings, I wouldn't use spray foam in the roof or walls of my house. When you can't see a leak or other problems, that small problem is a disaster when it finally appears.
If it cant dry, its gonna die. In the event water does get in, the foam will never let the framing dry. Ive seen this happen to sprayfoam and fiberglass and plastic vapor barrier. From what i gathered The sprayfoam case was caused by not caulking the windows. And the other was an old barn where the exposed fasteners were beyond their lifespan in combination with being overgrown with trees and shrubs. Read: lack of maintenance. Id even say maintenance in both cases. Whereas the customer who had his barn foamed never checked or recaulked his windows. Love what you are doing Matt. Less the foam and engineered lumber, i dont enjoy breathing in glue dust.
They dont have a wood roof deck in the uk like the usa, they run wood battons horizontally across the rafters then hang and nail concrete or slate tiles on, nobody in the uk has a shingle roof. The roofs are not air tight whatsoever they are open vented roofs outside the building envelope.
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Seems the problem is installing Any insulation in the rafters without either reserving a soffit vent-to-ridge vent air channel above for drying or completely sealing the lower surface of the insulated layer from vapor transmission (or both). Rockwool in the rafters without these measures taken will still allow warm moisture thru to the roof sheathing where it will condense on the underside. And additionally as someone else mentioned a dehumidifier should probably be installed in these sealed attics as well anyways.
This is a good episode. I always have thought that spray foam may be good to warm an old house up, but might not be the best thing for an older home. If you design a new home and take moisture in to consideration then you're probably ok with spray foam. People often overlook rock wool, which is an excellent insulation and sound barrier for older homes. I own a 70 year old house in zone 4 and the roof rafters are 1x6, so I doubt I could get spray foam to work for me. I've focused on other things like rock wool, and other types of ceiling insulation, and replacing windows and doors with modern tech to get the energy efficiency that I need.
You want to kill the chimney effect first. Spray Foam The sill. Then the walls. I put aluminum double bubble across my rafters which were doubled up 2x4s on balloon framing. Then did the same to the walls and tapped all the corners and seams off. I didn't condition the attic. It has 2 windows and a ridge vent. I've Never had a moisture build up in the house. It all went out through the attic or never came in. Cut my heating bill by 80%...
ABSOLUTELY. IMO rock wool is a superior insulator that doesn't come with the problems spray foam has (like fire susceptibility, obscuring water leaks, etc.) I don't blame the government regulators being more cautious for their citizens.
100% sure that it is only a matter of time before you see: “if your home contains spray foam insulation you may be entitled to financial compensation” on tv
@ yes I have done lots of remodeling and the cellulose gets compressed and causes voids in the walls, unfortunately there is no perfect solution, I demolished a church last month and there was no insulation in the walls and not a single sign of mold anywhere! Amazing considering I am in the Deep South.
Good job. You may also want to look at the HSE (Health and Safety Executive) document referenced in one of the articles titled Spray foam insulation applied to timber sloped roofs in dwellings Modelling of moisture risk for retrofitted spray foam insulation in existing dwellings. They did the computer modeling and determined the risk.
Thanks for this Matt. Followed your stuff for years. I have been arguing this stuff for years. It's pretty logical to do this correctly. Even getting builders to consider modern build methods. If you would like I would love to have a chat regarding all of the science and issues around public perception.
Im not surprised. I think spray foam is going to go the way of the dodo bird. Prices shot up to the moon and haven't really come back down. You need specialized equipment and trained employees. It just doesn't make any sense outside of niche applications.
A building with a top hat (uninsulated roofline) is insurance. Turn or treat your attic as conditioned space with foam and the underlayment roof barrier had better be PERFECT or your foam will hide a leak until it's too late. I do not understand why that risk is taken. The issue is that the foam is functionally treated as if it's also a sealer no matter where it goes. There have been decades of black, soggy fiberglass batts that were treated the same way, with the same results. At least with batts you can yank it out in SECONDS if necessary. Please think of repairability, not just quick efficiency in the moment when everything is still shiny and new.
Good job calling out how poor or misguided workmanship and lack of understanding of the building science leads to poor outcomes. I'm glad you're doing this work to help builders make fewer mistakes, less waste and better performing homes.
Unfortunately, especially in spec houses there is quite a bit of poor and/or misguided workmanship. The risk is that a significant number of bad spray foam installs (particularly in climates that are very cold or very humid) will give the rest a poor reputation and cause increasing difficulty in getting insurance or mortgages. In practical terms the perception can be as much of a problem as the reality.
@@benz-share9058I want to reiterate this. For all this to work four contractors need to know what they are doing with spray foam. Being on job sites where the trades are out back smoking pot and basically putting the minimum effort into their work, where the subcontractor himself only shows up every other day to inspect his workman’s work . . . .this in Houston aint gonna work out well. We have far less sophisticated systems that essentially.
The framing contractors, the decking contractor, the foam applicator, the attic ventilation system, the roof deck and roofer. Matt even made a video on how this foam collects moisture at the peak, you got to know what you are doing to prevent it.
If a mistake anywhere in the build can lead to massive issues, I’d think twice before installing. Good craftspeople can still make mistakes
I'v been seeing this sort of nonsense since I used to read my dad's builder's magazines in the 1960s. Maybe I'm being a hard a* but the moisture issue seems pretty obvious. You don't use open cell foam anywhere near water- unless you're washing dishes with it. Who are the engineers who signed off on this? They should all lose their licenses. The companies, especially the principals of those companies should be paying to remove this stuff.
A large French boat builder known for cutting corners on structure (weak thin plywood bulkheads, also absorbent), uses open cell foam for deck structure, gluing the frames onto hulls. (Would you glue or bolt a house to the floor deck? ) The decks after several years rot and fall apart. My boat has a closed cell foam core for the deck. It's effectively permanent. meaning my boat will last 100 years at least.
Where do you find a company to do the job right they all cut corners and they use this crap because it is cheap. They never should have licensed this cheap crap in the first place.
I'm in Scotland, which is part of the UK, and we've recently put Kingspan between our rafters with an air gap so moisture can escape and not rot the wood. The issue is really as your second point - older houses here have no vapour barrier in the roof so small amounts of moisture do make it through. Spray foam here was frequently put in by dodgy firms looking to make a quick buck, and they would just fill the space in the rafters, which will trap moisture as the cold air hits the warmer air of the foam and condensates, rotting the roof at the condensation line.
What is Kingspan?
@@rsmith02 a fibre-free core rigid extruded polystyrene insulation
@@rsmith02pir insulation
He thinks he has to mind US Scotland is Part of the UK Thinking Americans Don't Know Geography... Hey, Bra, Americans fully known Scotland is Part of the UK, and of Course this Red, White, and Blue Bloodied American Ross knows Ross-shire was the Old Heart and Blood of the Highlands! But do you know the 1st Official Ross a name once Protected by Law Across the Empire, the Chief of the Great Clan Ross the 4th Earl of Ross Hugh Ross signed the Declaration of Arbroath a Percussor to the Declaration of Independence, and his daughter became Queen Consort of Scotland to the 1st Stewart King, starting a War for the Next Generation for the affront to Ross that was and the affront to come from such. Hugh Ross is the Ancestor to the Majority of Ross' in the Western World, and it was Betsy Ross' Uncle in Law Col. George Ross who was last to Sign the Declaration of Independence by Date. I bet you don't even know the Last Sea, is the Ross Sea, and Yet You Doubt Americans Geography Skillz!
I’m in Scotland too. Another problem is our roofs leak due to age. The roof will have little drying potential if you spray foam
I used to use a lot of spray foam. Then we did a reno on a house that had what should have been a pretty minor roof leak, but because the foam trapped the moisture between sheathing and the foam it turned into a catastrophic amount of damage. There are still situations where it is almost a must, but we use it sparingly.
question: why don't they put a drainage plane like dimple mat from eves to ridge vent?
This is exactly why I don’t use spray foam. Roof leaks are inevitable, and if you can’t see them you get a catastrophic mess
@@johnpowers1125 I'm glad I have a standing seam metal roof where the risk of leaks are very low.
@@BobPritchard I was thinking the same thing, when I do my next build I will do (Zip*closed cell)standing seam metal roof. Good call
This is the problem with closed cell insulation, you don't see a roof leak. So, open cell allows condensation to rot the roof, while closed cell allows a roof leak to accumulate moisture.
Insulation above the roof helps keep the wood from being cold enough to condense. Open cell below it helps a roof leak to be visible instead of rotting the structure. There are roofers in the US who won't repair a roof with spray foam below the roof line.
I like rockwool. Spray foam makes a mess to go in and renovate modify years later, plus fireproofing is a giant difference between them
It's also vapor permeable so not appropriate for an unvented assembly in cool climates. Would make more sense with a ventliation channel at the top.
Imagine the cost when someone needs to remove all that spray foam. Its literally going to be gluing everything together and blocking any visibility to water damage starting in the wood.
And rockwool is great for growi g weed so... that's another +1 in my book
@@rsmith02 they call them a 'maximum' ventilation thing- as when someone call a tissue kleenex or a refrigerator frigidaire
@@b0rd3n???, do you mean the kelvinator?
Here in Norway we basically don't use any spray foam. It's seens as toxic, worse when it comes to fire and higher risk for water damage. I think all of the Scandinavia is the same
ua-cam.com/video/w-MsPTD_14s/v-deo.htmlsi=ZbLqM4XhqQhrcoQ8 you don't say
Here in Finland I use cellulose insulation in the roof of my log house, and no vapor barrier - only a permeable air barrier. No issues with moisture build-up and easy to check for potential problems.
@ yes, real vented homes seems to be more back up here in the north now. See more and more of that kind of insulation
Rockwool is best.
@ jeg kan personlig ikke fordra å jobbe med rockwool, men det er mange som sverger til det.
Hi from the UK, the UK gov has a history of 'insulation' programs that are used as ways to make jobs. A lot of people who dont have skills end up with low paid jobs insulating houses, there are good people doing it but there's also a bunch that pop up just to sock up the government money before the deadline ends.
It always ends up with a lot of problems, it's a rush to get the grant money over a real care for the work.
We have the same situation here in the USA. The government has weatherization programs that are largely staffed by unskilled workers that are poorly trained and have no basic understanding of physics. These weatherization programs often lead to homes having mold, moisture and IAQ problems.
In addition construction quality in th UK is way below the rest of Northern Europe when it comes to older houses.
Welcome to capitalism ...
@@3nertia Wrong, welcome to perverse government incentives.
It’s also a UK class E combustible, (not great) Polyurethane spray foam is nasty noxious foams at higher temperatures.
Anyone who installed as part of any insulation program, should be up for fraud and anyone who has this in are rented properties loft and not ripping it out should be up for corporate manslaughter if the property does a Grenfell.
Howdy from a Texan ex-roofer (with young knees LOL) that lives in France but previously all over Europe/ME. First problem is that Roofs are NOT built like in the USA ... where we install plywood/OSB over the trusses and then apply a tar paper layer before asphalt shingles. Here it is def "open air" with clay tiles resting on batons and nothing but the wild blue yonder between. Throw in high winds (especially in the Athens area of Greece where I even lost tiles in high winds) in rainy conditions and you've got a "colander" type roof; your reference to 1x4" might be typical in the UK but nowhere else. Also keep in mind the Trusses rest on cinderblock or concrete wall structures; in Israel, the roofs are solid concrete in some cases ... sort of required in a Country where EVERY house/apt must have a "Mamad" or bomb shelter of high KSI reinforced concrete and it ain't just "rain" coming down like now. On a side note, Hurricanes and Tornados don't really cause much damage and the USA should learn from this construction method ... not much more expensive for new builds but would require a re-train of our crews ... much different approach.
Anyway, I'm with the Insurance Companies on this one ... if the roof isn't sealed, rain/dew will certainly shorten the life span of the trusses/timbers as the spray foam is on the wrong side of the equation (trapped) ... "black mold" is worldwide BTW. So on a retrofit, clay tiles need to be remove, plywood/OSB installed and tar paper laid before reinstall of baton/tiles. "Governments" ??? What are ya gonna do??? Same ones that allowed "Lead" to be added to our Gasoline back in the 1920's just to quieten down valve trains ... not well thought out. We'll see how Solar Panels fare. Cheers.
Very informative comment, thank you. I've seen a few videos in the past about concrete homes and wondered why they weren't more popular. Seems like they would do better in severe weather. I'm not a builder, just curious.
As I see it, the issue is ventilation. Provide adequate roof ventilation, and this should be a non issue. I don't think it has anything to do with using osb sheathing. And almost nobody is using "tar paper" anymore... nobody who builds quality anyway.
@@TimTimTomTomI just took the tar paper off my 100 year old house and it was in great shape. Replaced it with more tar paper. I'm not convinced tar paper isn't quality. 🤷🏻♀️
@@TimTimTomTom ... and you live where? Want to nit pick over tar paper vs plastic wrap or plywood over GP water resistant sheathing ... everybody's got their opinion. But my point was neither is used traditionally in the UK or EU ... and when the wind/rain is coming at the roof horizontally, all that water will be trapped in the foam barrier instead and initiate rot; the reason for the content creator's post.
Let's be clear about "tar paper". I am 70, worked in construction before retiring. I have seen very few houses with actual "tar paper", and those were old houses. Newer construction ( most of my lifetime) uses "felt", which a lot of people confuse with tar paper. I had my own roof replaced in 2014 and they stripped and reinstalled 30 lb. felt, before laying the fiberglass shingles. Not putting the felt is kind of foolish in my mind as it insulates ( however slightly ) and provides additional barrier to water penetration should any get through the roofing.
Matt, here along the Gulf Coast in the US, non-native Formosan Termites are causing a LOT of problems. And the closer to the water you live the worse it is. Recently, I wanted to upgrade the insulation in our attic from fiberglass bats to spray foam. But I quickly found out that our termite company (Terminix) would drop us (cancel the bond) if we installed spray foam - for fear of trapped moisture which would in turn attract termites. Called other pest control companies and they said the same thing. Talk to your builder buddies in Houston about this. It is a BIG deal along the coast as every single home on or near the water has had a Formosan termite infestation. The Formosan termite colonies are an order of magnitude larger than normal subterranean termites and so they eat a lot of wood in a short time.
Good to know, I was always a little sceptical about this.👍🏝️🇨🇦
😯
I've never seen any insects in foam. I have seen it in every other type of bat insulation. They love to nest in that stuff and once it gets wet it never drys out.
@TheWhale45
I've seen insects in foam. Insects that because encased in foam because they were hiding out in crevices when I shot the foam. 😂
We should build a wall and keep them out
I’m not a fan of anything “permanent”. If you can’t disassemble what you assembled, you can’t fix anything.
I agree with you and like your comment. Question: Are you also a bit older? I only say that because I have been a building contractor for about four decades and have seen many products not hold out as represented. A popular product "PEX"warranties 25 years, copper 50 years. 25 years is not very long buried in a wall of your home.
Absolutely correct. I live in an 80+ year old home and have been able to renovate and repair much of it because it’s all accessible ( water damaged fiberglass insulation, insulation in the wrong places, leaking pipes, substandard electrical wiring, etc.). If any of this was inaccessible, we’d be looking at a demolition and rebuild. Radiant heating embedded in concrete? You are putting a lot of trust in something that will be a nightmare to fix if it fails.
@@janking2762 Very true.
@@fsoileau I respectfully disagree with your Plumbing analogy. We don’t know the lifespan of PEX yet. Just because the warranty is set for 25 years doesn’t mean it’s not good for longer. We’ve all seen copper lines that are well over 50 years and are perfectly fine.
I have seen copper lines that were installed touching a dissimilar metal and have corrosion to the point of failure. It comes down to how it is installed same as PEX
You have missed the point why the mortgage companies are unwilling to lend on spray foam insulated houses, while doing a great job of explaining the science. The issue is that the roofs with spray foam are hard to inspect for issues (especially caused by damp) and together with a significant number of poor installations this has led mortgage lenders to refuse to deal with spray foam. The idea of mortgage lenders or insurance excluding certain categories because they are awkward to deal with is certainly something that happens in the US, too. It doesn’t have to be spray foam insulation.
The next problem is most of these houses have to pass a blower door test when they test for air tightness, the regulations are getting tighter. I’m seeing some builders not pass the DET(duct envelope tightness) test because they didn’t spray foam.
If states want their houses to get tighter without spray foam….a lot of builders arnt going to get their certificate of occupancy. It’ll be the builder apocalypse
PEX is an example. I've gotten quotes from a few insurance companies that will not insure with PEX plumbing (and no, I'm not confusing it with PB).
Properly installed closed-cell foam can be a real boost for increasing the durability, comfort, and energy efficiency of the housing stock. Eliminating that option by refusing to insure it, is a bad move _in the long run._
In the short run it makes sense from the insurers' point of view, for the reasons you stated. What needs to happen is that the UK government needs to have more demanding education and training for insulation contractors, so that they know the right way to do things. This applies to building inspectors as well.
With the contractors properly trained and regulated, the building failures won't happen and the insurers will be able to take on an appropriate risk level.
@@MrDbraultwhat is their issue with PEX? the only issue with PEX is not installing the fittings correctly. Assuming the job was done right, it's good for a hundred years.
@@Tr-mx3qs It's a lack of imagination to think that only spray foam can deliver an air-tight house.
English carpenter and gc, now living in VT, USA.
Spary foam was and often still is sprayed directly to the underside of roofs in older houses which are more often than not tiled in slate.
The foam is sprayed to the back side of the slate.
condensate forms on the rear of the slste, and air flow is now restricted meaning the moisture has no where to go and so rots the timber frame roof, that supports the slate.
Meaning a whole new roof needs to be cut, then slated to remediate the problem.
I think you missed the comment where she said that she had black mould prior to the install. That is very common here, and indicates that there was already a problem with condensation to start with. The high humidity here means that people don't really trust wood buildings.
One of the issues was the way that the grants were structured - it encouraged companies to quickly do a lot of installations with minimal / no training of the staff, and no consequences if something went wrong. So it did not matter to them whether or not the roof rotted afterwards.
Absolutely. Humidity is sky high (70%) and in winter people do not open windows (even in bathrooms) and few people use dehumidifiers.
@@ChrisLubinskiwow, 70% humidity in winter?
@@Ed-ym4tu Average humidity for the last week outside was 96%
Hi from UK.
Really interested to see this video Matt. Our Health & Safety Executive (HSE) have just issued a report on spray foam (no idea why as there is no H&S implication).
They say that the risk of rot varies according to roof construction, type of foam and and climate, but if done properly is not a problem.
Open cell seems to be preferred here, theory is so that moisture from below can pass through newer style breathable membrane as opposed to traditional impervious bitumen underfelt plus double height roof battens to ventilate under the slate / tile.roof. The HSE also advise open cell. Nothing is said about thickness or whether rafters should be covered..Vapour barriers unclear. Its just a mess.
I read that just one senior surveyor set this hare running, as he came across a couple of rotten roofs, and now everyone is running scared. The standard foam thickess used here is only about 4".
There is a bad history of closed cell being applied directly onto the underside of tiled or slated old roofs to "hold it all together" to keep the roof going past its life. Thats not good.
Cowboy operators bolstered by well-meaning government grants, have applied the wrong foam in the wrong sort of roof in the incorrect way, and badly.
Building techniques in UK have been changing, warm roofs are now a thing but that is fairly new. The more common traditional cold roofs need lots of through ventilation, with only 300mm rockwool type insulation on the loft floor. Lots of strong anti-foam opinion over here!
That lines up with so many stories I have heard from England on buildings. The regulators are extremely slow to address new tech, and by the time they do there are huge issues. And very aggressive opinions on it.
Like your comment on closed foam, it is great stuff if used correctly and not to cover up structural or other issues like you pointed out. So now closed has a bad rep because of it.
@@darkshardrex7589 UK doesn't do prescriptive design codes. It's very subjective with objectives you should produce. And as the Grenfell Tower Fire showed, there are a lot of people in the UK confidently doing design and construction very wrong. who are overseen by inspectors who apparently have no idea what they are doing and standards bodies in the pocket of manufacturers.
and that's the truth.
I just don't get why the UK can't learn from decades of experience in other jurisdictions.
@@rsmith02I'm afraid the UK are right on this one, spray foam is bad on so many levels in this application.
The problem I have encountered repeatedly in the US is that finding a good installer is incredibly difficult. It’s hard to know if people are doing things correctly unless you yourself are an expert. Had a mini split install recently where contractor made a subtle mistake welding (edit: not welding, brazing) the line set and this caused thousands of dollars in damage to the cassettes. The install LOOKS great. Inspector didn’t think to ask about it. My concern is that mortgage brokers and insurance may lump everyone together and cause problems for modern homes no matter if Matt built it or not.
I just made a comment about the lumping together. Big companies seem to do this quicker. Might have to seek smaller insurance co's to get coverage. Good to still be able to get coverage but limiting options isn't great.
Welding the line set on a mini split??? 🤔😯
Let's be honest. In some areas of the construction industry in the US far more than half of the workers aren't even supposed to be in the country in the first place. Of course they're going to take any and every shortcut available to them. Most of them don't even get paid per hour but get paid for job so the goal would be to do whatever you're doing is fast as possible.
@JustNo8808
You know what, l can be honest too. I've worked with a bunch of these guys over the years - talking about construction workers you pick up at home depot or wherever for day labor - work by the hour, get paid in cash at day's end. I don't know that they were all undocumented but no surprise if they were. The point is, they frikkin work. I'm sure there's exceptions but the guys I've worked with were friendly, respectful, focused, followed instructions, asked when unsure, and strived to do the work as expected. We'd get their numbers and call them back whenever needed for more projects. They were cheaper and better than calling some established subcontracting company that might get to you the Tuesday after next and then be delayed, and when finally on site do things their way instead of how we wanted it done. Americans literally did this to themselves; I'll take hispanos all day long!
(That doesn't mean I'm for illegal immigration; I'm not. I'm for LEGAL immigration and carefully vetting everyone allowed to immigrate. I'm looking forward to the incoming administration sorting out the mess of the outgoing admin)
Yeah, not sure what that means.@elgringoec
Open or closed is bad for roofs. Issue is that if the roof has a leak, its make be impossible or very difficult to locate it. Water will pool & rot the roof. Either batts or cut peices of rigid foam panels should be used instead. You can always remove them for inspector or roof repair.
I suspect in the next 3 to 7 years there are going to be a lot of US homes that need roof replacement caused by spray foam.
You pretty much got it spot on. Good explanation. We have very different houses in the UK. Mostly clay tiles, poor insulation.
I live in South Florida and I have had to do WDO inspections for home refinance. There has been issues with homeowners Who have put in spray foam insulation and cannot get bank approval.
For the most common reason of it, making it inaccessible to see if there is or was termite damage that's being hidden/ iconcealed by the insulation. It also prevent us from being able to treat the exposed wood throughout the attic in a preventive fashion against wood destroying organisms using profucts like bora-care or premise2.
As a UK PassivHaus architect and project manager, I applaud your channel. I have been advocating that we need to build more like Americans here and move rapidly away from the so called traditional methods favoured by UK contractors.
I would strongly disagree with you, from experience of being from the UK and having family in the USA we should not be copying them.
We have historical and economic reasons not to build in timber as the supply is not local and costly in comparison to the USA.
Matt also references Dr Joe Lstiburek constantly, and rightly so.
If you watch his lectures on the perfect wall or the institutional wall which will last and provide good performance for centuries then he basically describes the UKs standard brick and block cavity wall used in most houses today.
Architecture jumping on the latest fad, like timber frame construction also cause reactions in regulations like the new part O, or overheating.
Ignoring the fact that it contradicts part k and m for window guarding, the elephant in the room is no consideration is given to thermal mass in any of the calculations required for building control.
This is not the case in Germany for example and makes light frame construction look great on paper but it's an illusion.
The USA are heavy users of aircon, but with thermal mass it just isn't required especially in the UK where problematic hotter weather only lasts for a few weeks at most.
The Romans knew it, the Greeks did, they still use it in the middle East and some parts of Australia now.
A couple of years ago with 34c outside my living room 1910 cavity wall direct lime plaster on engineering brick with 150mm natural yorkstone exterior with a 30mm cavity didn't rise above 22c as tracked by digital thermometer and humidity sensors.
My mostly timber framed well insulated room in the roof however didn't drop below 30c
My point is copying someone else's homework for English literature may not help you in a French class if you get my meaning. The UK and USA have different resources and climate conditions, resources and physics dictate what will work economically not fashion.
@ follow the building science. And building in brick is cheaper??? 😂
@@colinmendelowitz249 no brick has nothing to do with it.
In fact a lot of the house builders are looking to go timber frame as that's cheaper!
The performance though is inferior in most ways other than speed of build and possibly air tightness but that's debatable.
@@nathanlegge7090 Thermal mass is indeed a good thing, but it's also usually very high-carbon. There is a tension there. It can be offset by very long lifetimes. Passivehouse says nothing about timber vs brick vs concrete vs whatever - it's all about building physics that adds up. And it removes any issues with condensation in the wrong places, and makes very comfortable houses with tiny heating loads, that don't overheat. The art is building good houses without an epic up-front carbon cost. Less brick and concrete generally helps with that, but stone can be very low-carbon if it's not had to come too far.
@@nathanlegge7090well said!
While properly installed closed cell insulation with no leaks will solve the problems from vapor condensation, It can greatly increase the risks from bulk water from above when the roof fails. Yes, some people replace the roof when a periodic roof inspection indicates that the roof is close to end of life, many people first thought of roof replacement is when the brown stain in the ceiling gets larger and may take a year or more to figure out how to pay for it when they get an estimate of the cost. By that time, it won't just need a few pieces of roof sheathing replaced, it will need much more sheathing which is still glued to the insulation where it hasn't rotted to mulch and roof rafters with it. Won't it be fun to rebuild those trusses. Much of this damage will be done before any water gets through the closed cell foam to leave the brown stain on the ceiling.
Having lived in the UK for over a decade, coming from continental Northern Europe, the type and quality of construction in the UK is shocking. It’s not only the cold climate, it’s the year-round humidity, and that they absolutely weren’t building for it.
Your comment that some house are “under-insulated” made me choke. There are buildings here as recent as 40 years old that have either 2-3 brick thick solid walls, or a 2 brick thick wall with a totally empty cavity in between. No underfloor insulation, no roof insulation, just the expectation of cheap natural gas for all eternity. To the point that the only way to adequately dry out your house is to have heating on 24/7.
The spray foam roof insulation ‘scandal’ is the result of an endemic culture of short-sightedness coming home to roost, not only once (when originally built), but twice (when foam was installed). New requirements here finally got higher air tightness and requirements for mechanical ventilation (ERV/MVHR), but even then the homeowner rarely understands what it’s for, what it does or how it’s supposed to work… much less maintains it properly.
The UK's maritime climate means that an indoor RH of 50% and upwards is common.
I believe you were underestimating the average relative humidity in the UK. In addition to that due to the high relative humidity outside, there’s going to be a certain amount of water vapor that penetrates the roof and is then trapped between the foam and the roofing material. When the temperature drops there’s not time for the moisture. to escape, and consequently will condense.
Matt, most of the pre 1920 properties in England are slate or clay tile fixed on timber (lumber) battens fixed directly to the top of the rafters with no underlay, roofs then started to include a layer of roofing felt below the battens with this becoming the norm from about 1950. The use of timber sarking boarding above the rafters was generally only used on higher quality/status buildings, it has only become more common on domestic building recently, especially where there is habitable accommodation within the roof space.
Spray foam only really began to be used in England from the 1980's and then generally only for retro fitting, its use mushroomed about 20 years ago when there were government grants available for installing insulation to older properties, this attracted many unscrupulous installers with little building science knowledge to promote it for totally inappropriate situations who then often had very poor inhalation procedures.
yup inhaling foam is bad for you.
Hi Matt, UK roofs typically for the age you are talking about and even modern builds are felt underlayment, battens and terracotta tiles, plywood sheeting is not normally used. The loft spaces are built as cold roof, modern (last 30 years) will have ridge and soffit vents.
Worth noting building regs are different in Scotland, where sarking boards (i.e. wood sheeting) is required.
I put a layer of ridged foam between the decking and spray foam. If the decking needs replaced we should be able to peal the bad decking off without touching the spray foam. Time will tell though
I'm from the UK and the house I'm in had this. The survey report was basically what you said, so nice analysis there. In the end I offered the seller £20k less because of this and I had all roof tiles replaces which was quite a big job.
That house looks more like 90-100 years old rather than 40. Roof structures in UK are generally very different to US.
"Under insulated" is an understatement.
Recommended ceiling insulation in UK is 300mm (12"). Normal is fibreglass.
Tiled rooves on tar paper with battens is normal and as you say relatively breathable.
Your homes in the US are very different.
There was also an episode of Holmes on Homes, or another Mike Holmes show I believe where they removed everything due to the spray foam installer spraying the foam too thick up in the attic, thus it would never fully cure and was slowly constantly outgassing, which was making everyone in the home sick.
as a foam applicator your correct
@@stephenmitchell4393Technically correct, but could be misunderstood. So people understand - this has nothing to do with how many inches are applied in total. The problem arises when the applicator moves too slowly or over the same spot too many times before the foam can cure. Uncured product can get trapped behind cured foam and stay that way. It usually smells horrible, and therefore isn’t a danger because it’s caught.
@@nunyabidness3075 Right, as there is a difference between spraying 1 thick application, or spraying multiple thinner applications to create the same thickness.
Lived in the UK for a bit, can confirm. Huge caveat, the UK builds homes very differently than the US.
exactly.
People don't understand how important proper ventilation is.
It's an unvented roof assembly.
It's not important if it's sealed. That's the point.
A popular phrase I've heard:
Seal tight
Ventilate right
Yep we seal these up so much that the fresh air that used to permeate the envelope needs to be introduced mechanically.
The general public don't understand how important it is, but professionals for the most part do.
Build tight ventilate right is a good catch phrase but you have to know the likely failure modes and mitigate them.
Older designs have had hundreds of years of evolution to be perfected with local adaptations used for local climates.
Foam insulation, chipboard, osb and to a lesser extent plastics are getting that evolution now and it's proving some to be not up to the task or causing secondary issues.
Construction is quite conservative in it's approach for good reasons as the consequence of failure can be very expensive
I kinda have this debate often with people online. Spray foam is fine but you need to do a bunch of work first to make it acceptable, it’s best on new construction.
Please dont use Chat GPT as a source, it is consistently wrong.
Chatgpt can be very accurate if you ask it questions the right way. The best way I have seen it explained is talk to it like you are walking up to a random person that knows everything to ask them a question. If you give some vague question it will get confused. If you give it a very detailed question it will be accurate. I also never do what is called zero shot prompting where I try to get an answer immediately. I'll tell it what I'm trying to accomplish and get it to first explain the process it should take to get an answer and I'll usually also give it a role to play. Once it gives me that information I'll tell it to start to work through the problem. Especially with the new models they have it will spend a lot of time working through the problem. The funniest thing I did was I figured out a bunch of different "experts" that would provide good input and once each of them gave me an answer I asked them to have a meeting. It took a while to get the answer but the output was funny because it literally was a meeting where they ended up having meeting minutes and I could see them actually debating each other and correcting any issues they had missed. The output was 61 pages long.
@hotshot619 Yes, thank you for saying something. It drives me crazy the way people have come to just reflexively trust the Elaborate Lie Machine. It's designed to spit out sequences of words based on probability--it's not an actual, thinking researcher that can understand what it's saying.
I agree in the sentence that cgdp is a bad source of info , better search for info and go to
Links that is presented and sheck the quality of that info .
Whether stats in the uk : go to there whether afforety.
You're incorrect, chat gpt has an accuracy rate of 99.3 %
Source, chat gpt.
Great video! Thank you for making sense of this otherwise click-bate headline. I'm glad people like you are willing to do the work of what the old media used to do.
I am in Canada... and I removed all spray foam... everything was rotted.
I have douzen of pictures of the mess
Was the issues the same as this one- gaps where interior air condensed? Or was it a roof leak?
A really incompetent self handyman
.... I can write a book on how to not renovate... with all I found hidden in my house
@rsmith02
The extention the house, block all the ventilation, build a roof over a roof... a total of seven layers of shingles on over the others on a 2/12 pitch...
And they use spray foam to hides everything
@rsmith02
So the leaking of the roof was accumulating between 2 ceiling... until everything's fall down
I've seen someone do a fire test on that spray foam and I've gotta say that in a fire it actually boosts the flammability of the house. See the heat melts it and it just turns into oil which burns hot and helps keep the fire going and spread.
And is probably more toxic
This is part of why I never understood why people love it.
@@wobbuffetbuffet Because its cheap and fast to install.
No one who's ever had to fix a leak on the other side of some polyurethane foam wants to do it again.
Wow. Amazing investigative work. You probably hit the nail on the head.
Good video, the conclusions are good. You are low balling the humidity in the UK. Depending on time of year and location it can vary between 50% to 90%. Most roof construction is roofing felt on top of the rafters you see in the videos with batten nailed on top of that to hang the tiles from (tiles are nailed as required by building regulations) so not a lot between the cold tile and the inside of the roof space, nothing you would recognise as a deck. The big problem with this sort of work is the government grants for it. Companies will convince people that the the new (funded) thing is good for them and do the work, then get paid by the government irrespective of whether or not the house is suitable for the work or not. This behaviour repeats with each new government initiative to improve the (elderly) housing stock of the country.
America needs to establish serious trade schools that specialize only in residential home construction. Offer a graded certificate for proper completion of the required course load. Homes are too expensive to have knuckleheads being taught by other knuckleheads at homeowners expense. In my opinion knowledgeable craftsmen are in short supply.
Homes in the UK tend to sit at a humidity level of 50-60%
Yes or more in the attic. But also the ventilation at the rafters is missing in many of these situations, so there is often no path for the moisture to be removed.
@emcguinn2601 exactly that 👍
Regarding roof tiles, having lived in a 2005 built property, the truss was covered in a sheet of membrane (plastic), then 1*2 battons and then concrete tile.
This was very very common by builders such as Persimmon, Bovis, Crest etc etc
Should probably be cautious of ChatGPT results when they don't have sources cited. Could just be completely made up.
I wouldn’t have thought that the humidity in a typical UK home would be anywhere near 35%. Do most UK homes use forced air heating that would lower humidity. The weather in the UK is typically humid and the weather is typically rainy almost like Seattle.
Cheers from Canada. Been a guy who has built 2 - R2000 homes - 20yrs before they were adopted. Working on a NET ZERO. heavy insulation wall and ceiling, Double 1980 standards. It was a response by NBPOWER executives to the 73 OPEC crisis . Our area - is - 50 F. We need to release water - and decrease moisture into the house. For years - I have used - forced air movement. Thank you MATT - cheers!
Check out “ this old house-net zero bungalow, season40” believe it was based in Rhode Island, not as cold as you wrote but was a pretty cool build.
The predominant feature of UK climate (not that we have 'climate', we have weather) is the damp.
Relatively high cold temperatures feel bitterly cold due to the humidity.
We have a saying : too cold to snow. This comes from the times it gets really cold is when there aren't any clouds.
Ventilated antics are tried and true. Much more forgiving than unventilated antics.
Sure, just ignore the squirrels running around and pooping everywhere, and ignore freezing your ass off in winter or paying $400/mo in summer to air condition the place. Ventilated attics are OUTDOOR SPACES.
Nah. I sprayed my roof deck 20 years ago. My attic looks beautiful to this day.
@@Crusader1815if you do insulated rafters with narrow outdoor venitilated slits under the roof boards ( like 2") you can have full room height, and get a nice" non boxlike" room volume.
Love watching your content being in the UK its really interesting how in some ways your are ahead of us and others we are ahead of you.
.
That house your talked about was likely built in the late 60s-70's. That vertical "waterfall tile" on the 2nd story was popular then.
Houses into the early 90's were usually built with rafters and later trussed roofs were utilised. So your correct that they are typically thicker timber than a truss roof construction.
The major difference in roof construction though is the UK uses unconditioned roof spaces versus the usual conditioned roof in the USA.
Most construction I have seen on your channel for the USA uses OSB, ZIP or similar as part of the external roof substrate.
UK houses of that era, unless they have been re-roofed (which is not typical, roofs in the UK will often last upto 70 years+) used a bitumen/felt underlayment installed underneath the roof tiles (modern construction now uses the same materials I see in the USA, depending on roof construction requirements).
So when you only spray foam insulation inside the roof you impact the ventilation characteristics which generally results in condensation leading to wood rot.
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The more appropriate method of retroactively insulating the roof itself would be to install a small spacer, say 15-25mm around the edge of the rafter space (creating and allowing an air gap between the roof underlayment and the PIR - exactly like you have on your wall siding) and then cut 75-150 PIR foam insulation to the size and use Gapo Tape or Sealing Tape around the edges. This allows for greater insulation values to be installed in the roof whilst maintaining the necessary roof ventilation.
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The reason that this has become a problem is twofold:
Originally it was one of several approved retroactive insulation methods that met the requirements of the "Warm Home Initiative Grant Scheme" set out by the UK Government to reduce heating costs for the lowest income households and the worst performant housing stock in the UK.
The second is that whenever UK goverment funded schemes are setup there is a mad rush by lots of unscrupulous companies to cash in. This led to many "cowboy builders" spraying foam insulation without any care or consideration of the reason that properties were built the way the were.
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This is still the case now with the UK's push to Net Zero and increased emphasis on Air Source Heat Pumps. Currently we have a £7,500 grant available when an ASHP is installed and a Gas Boiler removed. In the very early days this was pretty much only taken advantage of by high income households. It should have always been a "means tested" grant ensuring that those with the least money and typically highest heating costs benefited the most.
When you consider that a Gas Boiler replacement can be typically carried out for £2000 or less (mostly just a replacement unit) but the average cost of installing a Air Source Heat Pump is £10,000-£15,000.
This is due to the different requirements in convection radiators at lower temperatures:
Gas Boilers run 70'C Flow/50'C Return historically - current standard is now 50'C Flow/30'C Return versus Air Source Heat Pumps anywhere from 35-46'C Flow/30-41'C Return
and heating pipework from the ASHP need to be larger due to the increased flow rate (Heat Pump flow rate is 4 times a Gas Boiler).
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Up until sometime around the 2000's we used to have local government employed building inspectors but in an effort to reduce expenditure by the Conservative governments and to decrease "red tape" and increase the numbers of house building a large proportion of the building inspectors were made redundant and the responsibility conferred to the house builders themselves.
So they now employ the building inspectors themselves. Even though building standards have increased there is obviously a conflict of interest between the enforcing the building standards and keeping build costs low. Typically you find that the "good building inspectors" who enforce the standards rigidly are not employed for long by the house builders in favor of those with more lax standards....!
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We also have a situation where houses that have flooded or are built on flood plains are no longer insurable for flood damage once the Government backed insurance initiative ends in 2039
www.floodre.co.uk/about-us/
Spray foam doesn't work well in homes built 100+ years ago, because the home was literally built to breathe to dry out. It is a very different concept that we have today.
Air flow in walls used to be encouraged, so that you wouldn't have mold. The issue is that this was a fire hazard as well.
If you take a balloon wall construction from the 1800s and the roof framing that comes with that, and you button everything up with open cell foam, you will get condensation on the wood and eventually it will rot.
2 inches of closed cell foam then I went across the studs with aluminum double bubble and then taped it all off. 12 years ago. No problems. I did not close up the attic. it was vented and had 2 windows. Cut my heating bill by 80%. needed a/c 2 weeks out of the year. Never saw a bug ever again. Never heard my neighbors ever again.
Retrofitting can certainly be done, but the whole thing has to be re-done. Pull the shingles off, clean it of any mold, replace rotted boards, then use a modern water/air barrier. None of those skip sheathing boards either. Seal it up, then use enough closed cell foam to overcome dewpoints, and have it properly installed. Roofs and walls are systems, and the components of systems must be engineered to work together.
“Built to breathe” haha more like “Built sloppily because nobody cared “
@@pb7379-j2kI completely disagree with you. A hundred years ago and more people took pride in their work. They used locally sourced materials that were cheap and very sturdy. They heated with wood that created more than enough heat to cook and stay warm regardless of how cold and windy it got.
@@Ed-ym4tu Yes, I'm sure they were master craftsmen with no question the best quality materials. The wind that whistles through the walls of old houses was on purpose I'm sure LOL
FYI, the UK is relatively humid. Expect roughly 60% humidity indoors even with some use of a dehumidifier, and 80-95% humidity in an uninsulated loft. Even without spray foam involved, it's very common to have condensation issues if additional ceiling level insulation is added, cooling the loft. Middle-aged housing stock (say 1970s) has non-breathable bituminous sarking felt under the tiles and typically relies on gaps at the eaves for air-flow - which may be blocked by extra insulation or boarding laid down for storage. Without adding felt lap vents or ridge vents, it'll be raining inside just from warm moist air leaking into the loft and condensing.
Makes it easy to see why spray foam would be an issue. You're still getting warm moist air escaping into the loft, but now it's condensing right at the rafters with no ventilation to dry it out, migrating through the foam as you say. And if you encapsulate the rafters, no-one can inspect to see if any water is getting through the tiles - so neither open-cell nor closed-cell foam is really acceptable for a retrofit.
I agree with the humidity, as a Brit who moved to Massachusetts it is incomparable. 60-70% compared to 30-35%. Also the weather, it pretty much rains or is damp every day in the UK from November to March. In Massachusetts in December to February it is super cold but dry.
Another thing is Brits tend to air dry their clothes in their house, Americans just use a dryer as electricity is so cheap, like 1/2 the price.
Well nuanced vid, Matt. I'm glad I'm subbed.
Great video and super-helpful presentation of the available facts and info-thanks, Matt!
Ooooof man, Ireland is not part of the UK.
Northern Ireland is, but given that he mentioned Wales he's probably aware of that and may have simple misspoken.
@ could also assume being American that he simply does not understand the difference between wales, Scotland or Ireland 😂
No one cares,
There are like 5 people that live in Wales.
@@cullenstagg I guess when you last visited Wales, they heard you were coming so ran away (everyone except the 5 deaf people).
I saw this news when it came out and remember thinking, this should be no surprise. When so much has to be perfect, along with installation, then that's just nuts to put your faith in that many unknowns. Better to keep things simple that can be repaired easily. My house is a medium size that i took certain precautions with when i built it and i would never want my roof deck insulated. My house is very comfortable and not drafty and my heat pump can condition the house in a hard winter in the south for $80/90 mo which is excellent and summer AC is only $60 when i observe peak hours. So insulate but keep it simple and don't fall for a lot of hype from those who want to sell some grand vision of miraculous products that are going to let you heat your home with a candle. You could wind up with rotting and unbreathable, nasty homes. I don't want to be tied into the systems any more than necessary and means avoiding repairs in a super rich labor environment.
Matt may I suggest you reach out to Roger of the Skill Builder channel to understand how most UK houses are built
The issue is spray foam is being used to cover up structural issues and mold. It can also trap moisture. Nearly all homes in Europe are 1970's or earlier built.
Houses in uk are built differently to the Americas we have totally different weather patterns
Thank you Matt. This is the technical info i wanted. I knew there was a logical approach to condensation in living spaces. Keep it up dude
Another comment regarding moisture control:
It’s my position that you will never be able to completely keep moisture out. Even if you did, I’m convinced the seal would fail over time. A “tight” house is a trap for moisture.
Instead, I focus on what I call “moisture management.” I assume moisture will get in - so I make sure there’s a Way for the moisture to get out. For example, I advocate installing siding with a small gap between the siding and the moisture barrier. That way, any moisture that gets in can drain out. I ensure there’s a clear air path on the underside of the roof, from attic vents to ridge vent.
Entirely depends on how you define "Tight." You can have a house with minimal air leakage while having that gap. Since it's outside the envelope.
I have no idea how I landed in this video but it was fascinating and you explained it very well even to someone that knows nothing about insulation.
Matt, Robin Clevett is the one to meet.
Agreed
Good on you Matt for doing a deeper dive on the story. One of the ills that has grown out of the digital landscape is a tendency to take in a headline and little else. Throw in the obligatory shock factor built in to the headline to encourage clicks, and it makes the "drive-by takeaway" that much worse.
This reminds me of a video you released about 3 years titled "I’m recommending we NOT INSULATE This Old House"
The historical context and designs used on these old english homes is not being taken into consideration when adding insulation. They could even have these issues with normal rockwool or fiberglass insulation if installed in the same way.
My parents' home, built in the 80s, has spray foam under the roof BUT sheets of rigid foam were tacked up underneath, leaving a 1-inch gap between the roofing material and the sheet. Foam was then applied to the outside of the sheet, allowing air to flow under the roof from the eaves. Never apply foam directly to the plywood or whatever the underside of the roof is made of.
Before I watch the rest (I'm only 2 seconds into the interview), Im going to veture a guess that (like everything else HVAC related in GB) they are doing it wrong; Government subsidies caused a bunch of businesses to spring up overnight without proper understanding, training or expertise and a whole lot of salesmanship (backed by government messaging).
Now back to it, let's t see how my prediction holds up.
I concur. We had our city mandate on homeowners to put water pressure regulator. They said that if we do it within two months, we can get reimbursement, but if we don't, later on we will have to foot the bill. They even gave us suggestions which companies to call. After install, it needed to be inspected by the city inspector. I called and guy was send to our house in 2 days. I checked during those days about total cost and the highest price for top tier back then was $95. City stated that they will reimburse up to $850. Notice word "up to". The guy came, did it in 15min and charged us .... yes you guessed it, $850. Then magically city Inspector for which the wait time is usually over a month, showed up 2 hrs after job was done. We both went into crawl space and thank God he came so fast (although I found out later that they scratching each other's backs). The water was dripping and since we always had bucket sitting under crawlspace water shut off valve, I had already about 1 /4 of gallon of water in a bucket. I panicked and told the Inspector that I will call the guy to get his butt back right away to fix the leaking issue and a da... Inspector tells me " don't bother him, it will be ok. In time the dirt and and grease from the surrounding area will plug up the connection and act as seal and stop the leak. I know that guy and he is always doing a great job". That's when my red flag went up. The city inspectors and other officials were directing people to their buddies because there was "free" money flying around. I told his that I don't give a crap since I paid $850 for job that took 15 min and part for $95 (they probably had further discount) and based on travel cost of the company and per Hr labor, should cost on high end even if charging 1 hr labor, no more than $550. I called the guy back. He came back ticked off. This time I watched him like a hawk and it took him less then 7 min to fix it and no leak after that. I was furious because this city reimbursement money didn't come off the tree, it came for property taxes from all of us. People who couldn't afford to pay upfront costs and be home magically waiting during the week day hour for installer, got screwed.
I thought US government also provides tax subsidies for insulating homes.
From the UK here, you are 100% correct. Companies springing up and taking the Government money and doing an awful job and the homeowners then have to live with the consequences. Same thing is happening here now with Heat Pumps. Company’s springing up, taking government money and doing terrible jobs leaving the homeowners living with something costing them 4x the running cost of the perfectly serviceable natural gas boiler they had ripped out in the name of being green!
@@gund89123 It does, but it's for insulation in the general sense, not specific to foam.
Also, these are established industries in the states, with experience and established best practices. This is not to say that there are not shady installers making a mess of things in the states, there are, but it's not an entire sector that has just sprung up out of nowhere based on artificial incentives and promotional messaging (advertising) from government.
Great treatment on this topic... I'm originally from USA and have been living in UK for 11 years... it's horrific here in terms of damp and mold problems. The average humidity level in most homes in UK is above 60% for example, which drastically alters that dew point you spoke of so it happens much more easily. Further, even in homes using ceiling level insulation and no under roof insulation as should be done here, many of them do not have proper venting of the attic space, it's all closed in. I guess it is to be expected, the UK gov was until some point in 90's telling their citizens to vent their clothes dryers into their homes to help heat the home! After decades of doing that they then discovered the massive mold and associated health problems it was causing and stopped recommending people do that, which then became a recommendation to use condensing dryers. These are better, they do still provide a small heat boost, but they also still do put some additional humidity in the home... how much depends on the dryer and if it's condenser is being maintained properly.
I live in the UK and never heard that the government advised to vent dryers into homes. All the advice I saw was to run a vent duct outside except for condensing dryers which are relatively OK to vent into the room - but only just.
The real problem in the UK is that many homes have the kettle running almost 24/7 boiling water for the copious cups of tea consumed 🤣🤣🤣🤣🤣🤣🤣🤣
I'll venture a guess that no dedicated vents were needed when the tiles were just laid on battens, but with more felt and other barriers, the codes for venting didn't keep up with the changes. Here in the USA, vented roofs have a generous soffit openings, but with vinyl siding and foam sheathing popular in colder areas, that makes it very easy for a fire to migrate from a window to the attic, destroying a house in 10 minutes.
It can be moist but it must then dry completely because mold grows in consistently moist areas only. Excellent video presentation that really got me thinking.
Matt, thanks for the video. The 2024 International Residential Code, and its predecessors, deals exactly with this issue in Section R806.5-UNVENTED ATTIC AND UNVENTED ENCLOSED RAFTER ASSEMBLIES depending on climate zone. The issue that is being overlooked a lot of times is the air-permeability of spray foam. The IRC defines "air-impermeable" (for the purpose of moisture management) as "an insulation having an air permeance equal to or less than 0.02L/s-m^2 at 75Pa pressure differential as tested in accordance with ASTM E283 or E2178." Air-impermeabilty is used by the IRC in insulation to prevent condensation on condensing surfaces as described in the video. There are open-cell foams that are air-impermeable and closed cell foams that are air-permeable. Some open cell foams are air-permeable until they are applied to a certain depth and then they become air-impermeable. The details of each foam products performance must be observed and you have to dig a bit to find it. The details are in third-party evaluation reports published by multiple agencies, the ICC-ES (International Code Council Evaluation Service) as ESR reports (google your favorite foam), Intertek CCCR-Code Compliance Research Reports or UL ER- Evaluation Reports., etc. In my office we do not use the term OPEN CELL or CLOSED CELL as it does not accurately reflect the air permeability. The key for the consumer is to KNOW what is being installed.
Great analysis, speaking from the UK. We have a history of government-incentivised unsuitable home improvement initiatives that later have to be undone. Also see cavity wall insulation and external wall insulation for examples.
Cavity wall insulation is 99% a good thing. There are a few examples of disasters, but millions of homes have been done with few problems. EWI is even more of a good thing because you have to really screw it up to cause problems. Mostly that comes from doing it on the cheap and using siliconed-on capping rather than extending rooflines, which of course practically guarantees a leak down the back eventually.
You are quite right that some of the shoddiest schemes have been done under grant-funding, and we've had far too many badly-done stop-start grant schemes. That doesn't mean that govt money to improve the housing stock is a bad things, nor does it mean that cavity wall insulation and EWI are bad things. We actually need dramatically higher rates of retrofit for buildings, and the more of them that are EWI-based the better IMHO. It's usually the best technically and lowest-risk major insulation intervention. But like everything in building, the detailing and design have to be right.
One of your most informative videos….thanks for sharing
Glad it was helpful!
A building, any building, has to be designed as a whole. Modifying it willy-nilly is asking for trouble. Taking the advice of a bunch of UK politicians is always a bad idea
UK politicians are doing a fantastic job.... at destroying the UK.
I’m an engineer and I HATE the idea of spray foam insulation for entire houses. It is super hard to put fires out, it can mold easily, it constantly off gasses which reduces overtime, but is still there. Not in my house. Only as gap sealer
Matt, you are also missing a weird thing about UK homes and that is that they have water tanks in their attic. They have very low water pressure because of old pipes in the ground so they have to have water tanks in the attic to supply the house. I am sure that causes even more mosture in the attic that here in the USA.
Definitely that would add another layer of humidity which would exacerbate the problem
Don't be silly. It's just a closed tank with a breather pipe to the attic or through the roof. That is very very little evaporation.
My 1970s home has mains pressure water (about 3 bar) - hot and cold, no gravity feed.
Old central heating boiler had an expansion tank in the loft but that was removed and it's now a pressurised system.
That's a lot more normal than tanks in the loft these days.
Not a builder but something i’ve thought about that would help a lot of concerns is this- put an air gap. We use something near the eaves to prevent insulation from falling down there and lets the air in so why not run that from eve to ridge then spray under that? Keeps the air flow on the roof deck, so it’s cooler; doesn’t permanently adhere it to the deck making removing it and replacing it even more costly, allows leaks to escape and not sit and rot the decking. Idk if in practice if that’s good but it makes sense to me.
Insulation in the UK is generally very poor to non-existent in many houses, and I don't mean to stereotype, but most people's solution is to just put on a sweater and drink a hot cup of tea.
I ought to be outraged by that comment … if I wasn’t sat here in a jumper with a brew whilst reading it. 😂
@@mattundercoat it is what i grew up with 😆the attic at my parents place had about 2 inches of glass wool insulation which was dong absolutely nothing. Quick trip to b&q and now they have 10 inches, and you could feel the difference immediately
Must be hard to spot leaks and other faults if the roof is sprayed with foam
I imagine any leak in the roof traps moisture and causes woodrot.
open cell allows the water to pass straight through.
I seldom see spray foam installed correctly. Most often gaps result in effectively paying thousands of dollars for nothing.
Then I see deck deterioration due to moisture trapped beneath roofing and above the foam.
Bring the duct inside the space and vent the attic and insulate with mineral batts.
We closed cell spray most of our projects here (Washington DC area). Never had a problem. But we subcontract it out and the installer is really excellent.
Who is the installer?
@@geode232 insealators
Thank you for your analysis and information.
Matt when encapsulating an attic you need to purge 30 cfm. So humidity does not build up. The solution could be as simple as a Ecor Pro dehumidifier.
Purge and dehumidify are not the same...
Im afraid this is a problem that applies to US too, maybe not as bad as UK but still an issue. There should never be any insulation on the warm side of any timber roof components so if your concern is heat escaping from the building you either need ceiling level insulation with plenty of ventilation in the roofspace, or all the insulation above the timber deck and none below.
Glad that the build show is addressing the diference between the UK and US on spray foam insulation.
I live in London and most of our stock is Victorian then 1930 to 1970 stock. We have a very low new build rate.
we had you black mould creases in the 1980 with dry rot in new build timber homes. This lead to a reduction in timber framing in the UK. Most new houses are block and brick cavity construction.
on older properties, we did not have parking ( underlament to the US). As Matt points out we traditionally have on condition loft spaces.) No roof vents or poor loft ventilation. Moisture is Or was controlled by ventilation through the slate or tiled roofs. ( I am leaving out Thatched roof as that is outside of my practice area).
So spraying foam between the rafter is not desirable. As it creates condensation.
When roofs are recovered a marking is normally added. But is normally a bitumas membrane type. It not common to use a smart breathable membrane at this point.
There is also a tendency to use the foam on roofs that have reached the end of there lifes. Which is not appropriate. Hence banks and insurers .
A guy I know works for Aqua Barrier. He showed me pictures of a crawlspace under a home that had been sprayed with foam (open or closed I don't know. Assuming open). The house had to be demolished because the sub structure had all rotted out. I'd love to use foam in future projects but can't figure out what information to trust.
The only problem with spray foam is bad installers. That's why I won't use it, because I don't trust anyone to do it right.
Right mixture, right thickness, right coverage, right temperature, right amount applied in one area at a time, right dehumidiication system, right home to begin with.
Most installers don't underatand half of the required variables to create a safe install.
Agreed. Installer quality seems like a major variable. However, a procedure that is easy to do wrong, and when done wrong can lead to catastrophic failure, doesn't sound like a good choice.
What if its installed correctly but then you have a small roof leak a few years down the road that goes unnoticed? Then the rot and damage will be much worse with the foam essentially holding water like a pool. Anyone living in rural areas with extra squirrels, mice, birds etc... can always have potential for a critter to make small holes looking for entry and nest areas. So many things can happen over the years. Spray foam will be costly repairs for some people.
With 30 years of experience in architectural engineering of commercial buildings, I wouldn't use spray foam in the roof or walls of my house. When you can't see a leak or other problems, that small problem is a disaster when it finally appears.
If it cant dry, its gonna die. In the event water does get in, the foam will never let the framing dry. Ive seen this happen to sprayfoam and fiberglass and plastic vapor barrier. From what i gathered The sprayfoam case was caused by not caulking the windows. And the other was an old barn where the exposed fasteners were beyond their lifespan in combination with being overgrown with trees and shrubs. Read: lack of maintenance. Id even say maintenance in both cases. Whereas the customer who had his barn foamed never checked or recaulked his windows. Love what you are doing Matt. Less the foam and engineered lumber, i dont enjoy breathing in glue dust.
Also, foam makes it a pain in the ass to do renovations or repairs. And you can't put it back in, you have to pay someone to respray
They dont have a wood roof deck in the uk like the usa, they run wood battons horizontally across the rafters then hang and nail concrete or slate tiles on, nobody in the uk has a shingle roof. The roofs are not air tight whatsoever they are open vented roofs outside the building envelope.
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Seems the problem is installing Any insulation in the rafters without either reserving a soffit vent-to-ridge vent air channel above for drying or completely sealing the lower surface of the insulated layer from vapor transmission (or both). Rockwool in the rafters without these measures taken will still allow warm moisture thru to the roof sheathing where it will condense on the underside. And additionally as someone else mentioned a dehumidifier should probably be installed in these sealed attics as well anyways.
This is a good episode. I always have thought that spray foam may be good to warm an old house up, but might not be the best thing for an older home. If you design a new home and take moisture in to consideration then you're probably ok with spray foam. People often overlook rock wool, which is an excellent insulation and sound barrier for older homes. I own a 70 year old house in zone 4 and the roof rafters are 1x6, so I doubt I could get spray foam to work for me. I've focused on other things like rock wool, and other types of ceiling insulation, and replacing windows and doors with modern tech to get the energy efficiency that I need.
You want to kill the chimney effect first. Spray Foam The sill. Then the walls. I put aluminum double bubble across my rafters which were doubled up 2x4s on balloon framing. Then did the same to the walls and tapped all the corners and seams off. I didn't condition the attic. It has 2 windows and a ridge vent. I've Never had a moisture build up in the house. It all went out through the attic or never came in. Cut my heating bill by 80%...
Hire a company that thinks of the house as a system and chooses the right tools for the job vs starting with a product like spray foam.
Thanks Matt - always great content and great research.
Cliff Notes version: UK, you're doing spray foam wrong.
😁
Great explanation matt! Thank you for this
I hate spray foam I only use rock wool
Same
ABSOLUTELY. IMO rock wool is a superior insulator that doesn't come with the problems spray foam has (like fire susceptibility, obscuring water leaks, etc.) I don't blame the government regulators being more cautious for their citizens.
100% sure that it is only a matter of time before you see: “if your home contains spray foam insulation you may be entitled to financial compensation” on tv
Rock wool and sheep wool. It’s too bad cellulose only lasts 20-30 years since it’s so eco friendly.
@ yes I have done lots of remodeling and the cellulose gets compressed and causes voids in the walls, unfortunately there is no perfect solution, I demolished a church last month and there was no insulation in the walls and not a single sign of mold anywhere! Amazing considering I am in the Deep South.
Good job. You may also want to look at the HSE (Health and Safety Executive) document referenced in one of the articles titled Spray foam insulation applied to timber sloped roofs in dwellings Modelling of moisture risk for retrofitted spray foam insulation in existing dwellings. They did the computer modeling and determined the risk.
UK has been that way for years
Thanks for this Matt. Followed your stuff for years. I have been arguing this stuff for years. It's pretty logical to do this correctly. Even getting builders to consider modern build methods.
If you would like I would love to have a chat regarding all of the science and issues around public perception.
Im not surprised. I think spray foam is going to go the way of the dodo bird. Prices shot up to the moon and haven't really come back down. You need specialized equipment and trained employees. It just doesn't make any sense outside of niche applications.
A building with a top hat (uninsulated roofline) is insurance. Turn or treat your attic as conditioned space with foam and the underlayment roof barrier had better be PERFECT or your foam will hide a leak until it's too late. I do not understand why that risk is taken.
The issue is that the foam is functionally treated as if it's also a sealer no matter where it goes. There have been decades of black, soggy fiberglass batts that were treated the same way, with the same results. At least with batts you can yank it out in SECONDS if necessary.
Please think of repairability, not just quick efficiency in the moment when everything is still shiny and new.
Starts at 6:00
Thank you
Great video, Matt. Well researched and well explained. Thanks!