I’m a carpenter and currently constructing my partners gym. All timber construction. Using the tape you have mentioned. Much prefer this method, it is time consuming but a better job. Couple of things to mentions: I do have a crown roof construction which adds to the overall outlay. Cost. The tape cost as much as the pir insulation for the whole build. Once you have a system going it can be quite quick to install tape. All in all this method will have to become the norm as we evolve in the construction industry I just hope the tape price will come down.
Please send over some photos would be nice to have a look. Yes, its better but very costly. I think we will be moving away from PIR insulation soon I will be showing a completely different way of doing things in an up and coming video using mostly much cheaper insulation and a quicker method of installing also more air open!
@@SteveRoofer I will do Steve. Thanks. I have subscribed to you for some time and you have certainly made me re think on the installations of insulation products. You are a credit to UA-cam.
In Finland we leave the foam insulation about 15 mm smaller on each side than the cavity and then fill the gap with flexible gun foam. That way we can ensure the gaps are filled entirely and no places for heat loss or air movement are left. We usually also add another continous layer of pir-foam on the inside (normally 30-50mm). This layer acts as vapour barrier, insulation and thermal break all at the same time.
Thank you for the advice, having recently done a hot roof myself ( also tested with thermal imaging) i wondered what they would be looking for. This video explained it perfectly.
Really appreciate this, spending your own time and effort to show us all this, very common mistakes like cutting the insulation board at an angle, i've heard that from many builders.
Its a hard job to get perfect cuts on thicker boards unless you have the perfect tools Bear in mind this type of work in a lot of building projects is given to unskilled workers who don't understand or aren't shown how skillful work it is to try and get it right.
I'm rebuilding my old 1880s house and am using Rockwool/Rocksilk everywhere with a membrane. Cut it 1/2" - 1" bigger than the gap and it makes a nice tight fit and fills up any wonkiness in the battens.
Thanks unfortunately now I'm not on-site that much I'm not getting the opportunity to film what I need however going out and doing loads of roof surveys is enlightening as the misunderstanding in all aspects of the building trade is just astonishing. Love the job you are on now it's looking good. Yes if there is an opportunity I'm up for it.
I think it’s important to be a little more clear on the definition of ‘loads of heat loss’ . As a previous comment mentions, what is the heat source used to record the heat transfer? Also what are the span parameter settings of the thermal camera. The images in thermal imaging can often look alarming but it’s important that the interpretation of those images is understood correctly to be realistic in the quantitive data. Thumbs up for the enthusiasm but those cameras in the wrong hands can be quite misleading.
In reference to the thermal camera, are you saying "please clearly define the colors in reference to how much of a change in temperature the areas are"? In other words, the visual "distance" between blue color on the camera and red is 0.5 degrees Celsius vs the "distance" between blue and red is 15 degrees Celsius?
The expanding foam absorbs moisture. This is why a thinner secondary layer of at least 25mm insulation over the studs is important as well as below the rafters. Even taping or sealing the external lining with another layer of insulation. We never use insulated plasterboard as you’ve then turned reflective insulation into convected insulation.
Although I can agree with some of your comments above I'm not quite sure about your comment on insulated plasterboard! By the time you've installed the plasterboard even if it's backed by insulation you are deemed to be internal and therefore you should have no problems.
@@SteveRoofer what about services coming through the wall ? Cables, pipes etc have to them penetrate the VCL for every socket switch pipe etc. every screw to install the plasterboard penetrates the VCL behind it. Here in Scotland we’re still 150 centres for fixing. That’s the equivalent of 19 penetrations from the face of the plasterboard into the substructure that we’re trying to prevent cold bridging from. The best way as we know to get rid of vapour is ventilation. There’s no ventilation next to either on the inside or outside face of a VCL that’s hard up against another surface. The other “issue” with insulated plasterboard is that it doesn’t prevent cold bridging from the substructure unless you’re able to seal all but joints between each sheet. And if you’ve got for instance a 72mm insulated sheet that’s probably worse than a steel penetration because it’s 72mm deep gap only stopped via the plaster or jointing compound. Where as if 25mm+ of PIR is installed over the studs then battened out again all joints taped on the insulation to create your insulated envelope you know you’re now not relying on any other measure of sealant. Any penetrations in the future of the building will not affect the VCL performance. What about radiators also. On an insulated plasterboard wall with a foil layer directly behind the plasterboard it won’t reflect heat but absorb it as there is no airspace to reflect that heat into. Heating up the mechanical fixings also. Helping heat penetrated the insulation more. It’s all little silly things but lots of little things can make that difference I believe. The least penetrations we can put in our walls where the VCL is involved, the better. No hundreds of staples. No hundreds of drywall screws, no multiple cables pipes or electrical boxes but into our insulation. Air circulation where you want it. Any moisture that may get behind a battened out wall over insulation has an air flow between the back of the plasterboard and the face of the foil. It’s also got somewhere to go. Directly down in the case of a malfunction. No need to seal plasterboard to floors etc. if anything you can raise it up 5 or so mm to help vent behind the board. It’s sure not detrimental to your sealed air. It seems a common practice though for big house builders to teach their workforce to air test after walls have been plastered. If we can air test at insulation level, we then know our insulation ins doing exactly what it is meant to be doing. Just my opinion though.
@@SteveRoofer standard with us. Some councils won’t allow insulated PB when planning for extensions. I believe there’s an issue with fire ratings also.
I appreciate there is clearly heat leaking through the badly sealed gaps between insulation and timber but it's a pretty small proportion of the wall as a whole. Surely the answer is to leave a ~10 gap all around and foam it. This would give a much more consistent foam installation and not only will this provide a better thermal performance through the foam - and the wall as a whole - but also, as you mention, much reduce air movement though it.
I’ve started using my table saw with an extractor to cut pir, it’s fast, clean and accurate. I thinking your using expanding foam you need to leave a 5mm gap all round to get the foam right in there, I’d be interested to see what works better- tight square cuts or loose cuts with foam around
Yeh whenever I foam in boards & I cut them with at least 5mm gap to get the foam in & use screws etc to hold the boards in place until the foam sets as fitting the boards tight sounds good but I always found you end up with some smalls gaps which you then struggle to fill because they are to small to foam properly.
@@SteveRoofer if putting that foam tape around every square of celotex is the only option it’s gonna make work so expensive we’ll be better of getting it sprayed. Side note- I done a loft and garage conversion recently, foil taped the loft conversion, it cost me about £600 in labour/wages. Stapled a vapour barrier on garage conversion, cost about £80.
Polyisocyurate PIR insulation is a cyanide based killer.all 70, Grenville tower folks died of cyanide poisoning in the fire fueled by this material. Tape the exposed edges and cover the lot with a vapour barrier to reduce heat loss but the inhabitants will be protected from the long-term exposure and lung damage this material will cause . Construction workers please use PP3 masks
Interesting video, with this in mind it may be an idea to change our construction so the installation can be installed without being cut, so maybe insulate in or outside the stud work
I think we will be moving away from PIR insulation soon I will be showing a completely different way of doing things in an up and coming video using mostly much cheaper insulation and a quicker method of installing also more air open!
I just made my own tape. A roll of expansion joint foam and a roll of foil tape. Costs less than a quarter of gapotape and does the same job. Little bit more work tho.
Can you post an example of the expansion joint foam…. I’m upgrading the insulation in my Dorma cottage… so far have just put insulated PB (72mm) over the top of existing PB (which has about 70mm of rock wool before the felt) I figured that because of the gaps PIR wouldn’t gain me enough to compensate for the mess of removing the rock wool and plasterboard… I am however going round with my thermal camera installing rock wool where there is none… However for the Apex I thought some PIR might help. Hence maybe using the quarter price gapotape….
The foil is not just a VB, but the performance of the PIR board is dependent upon foil facing either side. This also protects the insulation foam from decaying… this is probably why BC are asking for continuous foil. It all illustrates the reason for external continuous insulation.
I've been doing the second 50mm layer in my loft construction for years; no one told me; it is just common sense. If you build with quality in your mind, all types of changes take place in your build. The client pay more, but the end job and the economy in energy savings plus the comfort is noticeable.
I installed 142 mm alufoil-faced insulation for my workshop build. The external sheeting was already completed, so I had real problems getting a precisely cut sheet into the stud gaps. Effectively, the sheet was compressing air. I found the most effective way to get a good seal was to cut the sheet exactly 10 mm too small, insert the sheet, then fill the gap with foam, starting from the back of the space. Of course, a workshop doesn’t have the insulation and damp requirements of a house, but I wonder wonder if my solution would be acceptable for habitable spaces. Final point, I bought the Festool specialist insulation saw. Used with their track it enabled extremely accurate and square cuts in the insulation. Disgracefully expensive though!
Now that you have everything hermetically sealed...the timber will rot out and black mold will proliferate. Homes need to breath. Try looking up warm roof rotting problems in cold countries.
Since the mockup is open, I''m interested on what you use on the inside to generate heat. I know it is not important, but it will give the whole story so the viewers (and me) don't have to think about that anymore. I have worked for a company that does installation like this. Cutting the PIR insulation using a long Snap off Razor Knife and use expansion foam to close the gabs and tape the seams afterwards. The cuts will not have an 90-degree angle, the cuts will not be uniform. That company never uses a vapor barrier. They trust the aluminum cover and tape to perform that function by itself. As you tell and show, never expect to depend on one barrier by itself. Using foam tape, this will help to have uniform insulation, but this means cutting the PIR plates using something other than these snap off razor blades. Why do companies don't use better cutting equipment? Because it takes too much time, and time is money. This opens another discussion all together. Off course, the finished install that must perform as required and expected by the customer. The practical and the theoretical. It is difficult, especially retrofit installs. MY QUESTION: What will be the loss by not going for a correct installation? 1) Not having the correct 90 degree cut and correct size fit? 2) Not using foam tape? 3) No continuous vapor barrier? I could argue, the best install would be closed cell spray foam. But that means, no DIY. I see in the comments, you will show an alternative and better install using other(?) methods for the installation? I can't wait 🙂
I preheated the room with a fan heater for about an hour before taking a thermal imaging. I'm going to do some more testing with the insulated tape and see how that differs using the thermal imaging speak soon
Love your videos Steve. Would be interesting to see what the heat loss through those voids would be with 25mm pir on top off studwork and it being plasterboarded and maybe skimmed.
Any excellent presentation and an insight in the common day to day defects that are built into our buildings (not just homes) Unfortunately, over the years I have had to design and specify details that have tried to account for the general poor quality control on building sites rather than opting for the best performance. In this situation I would have specified multi-foil thermal barrier that can be purposely moulded around all of the elements and be easily taped with little or no damage to the integral vapour barrier. the speed of installation of the multi-foil offsets the perceived material cost premium so it can be cost effective and not only for heat loss. To add additional insulation in the form of PIR board on to the face of the studwork is easy and will be reliably jointed. Whilst your video is very instructive, I wonder how much heat is really lost and whether this is just a storm in a teacup reaction? Having said that there is no excuse for poor quality control as the customer is not getting what they expect.
Yes the point of the video is to show that we can and should be doing better, i'm a lover of molty foil because of its ease of fitting, however I still see it fitted badly lights cut thoug it. Edges not taped and sweating problems.
@@SteveRoofer Unfortunately Steve, you are in the minority when it comes to good practice on building sites. There is little care given to installations for example, how many electricians actually understand that they are doing wrong when they cut through the vapour barrier or insulation? You shouldn't have to teach every trade what they should and shouldn't do in each instance but understanding the very basics and principles of general building should be on the radar of every trades person There are too many 'General Builders' who are single tradesmen and know little about the various aspects of building .
+ use insulated plasterboard. on all perimeter walls. Just doing a big detached house with 75mm in the cavity with all joints taped with 100mm foil tape and 62/50mm insulated plasterboard on all perimeter walls and in reveals. 140mm in the floor and 100mm between the spar's. All sheet insulation cut at 355mm on a table saw using a special Japanese blade. Everything tight and sealed and overtaped Cavity block work completely OCD full fill, scraped clean and bucket handled, nothing proud . Should be toasty!
So for a pitched roof is it better to put a membrane inside the room, then insulation behind that, and then OSB boards for the roof and a membrane on top of that, too?
EXACTLY the issues in our loft converstion - built by the builder who owned the place before us, but apparently didn't think insulation needed to fit edge to edge. Big gaps around the celotex, freezing air blowing though roof space so if it's freezing outside, the interior of the plasterboard is about 12C even with the heating on. The downlighters of course have NO insualtion above, so would be frozen if they weren't conducting heat out of the room so effectively. Cold roofs are a bloody stupid idea, since they're all installed so poorly. 😤🤷♂️
Yes, it's unfortunate all this detail takes a lot of time, but when you are trying to something like reducing the amount of lost energy from the building, then you have to be more precise, but for some unknown reason they can't seem to work this out
Hello mate, sorry for being late. Im thinking about igloos, and adobe mud houses and wattle and dorb and it strikes me that this method of construction here is doomed to fail in install. Why are we building the frame then stuffing the insulation on, when in the past the insulation was inherent to the structure? I like your video - and this is actually a pretty half decent install. Ive seen people just stuff boards in with no real care, spray, tape anything really, then slapping the dry wall on, or laying the brick before the site manager comes visiting. I always say its like leaving your jacket unzipped in winter.
Thank you for doing this Steve. I have been retrofitting with PIR, using a tracksaw, to get accurate fits and it takes forever. I have an upcoming project so would be really interested in your proposed alternative to PIR.😀👍
Pir is just not the answer in older buildings in most scenarios as there is too much scope for poor detailing as insulation like pir wasn't designed into the building . Its great in a modern sips design.
Why dont you just cut the insulation 1cm narrower on each side and fill it up with foam?? No gap and full effect on insulation! Thats how i did and the house stays warm!
Everything you said is correct! You seems you know the details.. I have sub question which i need confirmation. When wee put bariers on both sides we basically trap air and humidity "between inside/outside space. And people are screaming.. wood needs to breath and it will rot.. and that is never endless story. Now these is my "logical guess" answer... 2 situations.. when we have new build and wood is not dray i would aggre with answer that wood needs to breath and prevent rotening and mold.. but in second situation when wood is 10 and 15 years old .. than it has stabilised and should not be problem with wood breathing or mold itc.. because it leaves in stabelised and unchanging enviroment. What is your professional answer.
I side needs vapour barrier and outside will have a breather version so moisture can escape but not allow it back in.still need the air gap at the top for air flow. Seems to be lots of these videos coming out for now and don't know why
When I was looking into PIR foam panels being placed in a wooden frame like that, the Kingspan website said that it didn't actually meet any standards until you placed a PIR backed plasterboard across in the other direction, and from there I guess you would plaster/skim it and paint it making it a complete solution?
Hello Steve, I’m a carpenter new to the UK from NZ where our insulation regs are a lot different. I’m doing my first build here for a client, and the original plan was a pitched roof extension with cold roof insulation. The pitched ceiling has now changed to a flat ceiling but still a pitched roof. Am I better off insulating the flat ceiling, or the pitched roof?
Hi Steve, stumbled across this video and very informative for understanding the importance of tight fitting insulation. You mentioned doing a test between three different installs, did you ever do that? Most times we do 100mm between rafters then full sheets of 50mm pir over the top to prevent thermal bridging between the rafters. With that in mind what is the most effective way of doing it? To me gapotap seems insanely expensive, I've always fitted PIR very tight however I'm starting to think it might be better to leave 5mm all the way around and fill with a low expanding low u valued expanding foam ensuring it's the depth of the board. Do you have any experience with the best performing option?
What that Gappo tape made from? The same precious gems as PIR? It will cost a fortune to do it properly to building regs. They are all in on it to rip us off.
I would be interested to know if multi layer foil is the not the simplest solution, no cuts, no gaps and no expensive tape. Use the foil as the first layer to "cover" the rafters/joists and then bulk up with whole sheets of rigid PIR and foil tape over the top if needed (depending on the efficiency of the foil I imagine)
I have the use of meny thermal imaging cameras as my son is a level 2 Certified Infrared Thermographer some of the cameras I use are 15K plus the one I alway use is one you fit to an iphone costing about £300!
I used my flir m625 on top of a friends barn to see what was taking his chickens here in wisconsin.....well its 9' tall with 19" footprints... enough said
I would put another layer of kingspan/celotex around the inside, keeping a note of where the wood is under it with a marker pen at the edges, maybe sandwiching a plastic vapour barrier in between the 2 layers so it doesnt get damaged. But what of screw penetrations? There is a butyl tape which allegedly seals up. I got to the end of the video - you did anther layer like this. It says the 'next' video shows how to do the holes from the screws.... maybe a second layer of battens cross wise? Maybe I remembered it from seeing the video before! I'm going to do mine in Spring 2024. Maybe I'll make a video with my plans before I finalise so youtube can criticise and improve it ! I dont want the OSB and beams to rot after ten years from condensation !
When i lived at home we had single glazed wooden windows, no central heating, no insulation in the loft or walls and just an open fire in the front room . But i never remember feeling cold or my parents complaining about being cold. Have we just become to soft?
With no stud being perfectly straight and cutting PIR perfectly also unlikely, surely rockwool is a better option for in between studs? PIR is a better insulator but the draughty gaps it leaves negate any benefit in my opinion. Plus it’s a lot more plastic for some poor sod to deal with later down the line
They insulated my bedroom and raised the ceiling. They never realized that it's a flat roof, It seems colder now than it did before they started. Will I ever have a warm bedroom?
Just came across your UA-cam video here on insulation and wonder if you did a similar study on Rockwool rather than just Kingspan ? I am thinking of using Rockwool on my very old house where they added an extension without much insulation as it is also breathable ? Your video does highlight concerns about how well Kingspan fits into Joists etc.. and the gaps it leaves. I was also going to cover the insulation with a thermal/vapour barrier foil. Just wondering if tere is any specific qualities I should look for for the Foil ? Thank you for sharing your knowlegde about this as it if very imortant these days and people just don't seem to get it!
I'm a lover of rock wall as it is fair open problem is it doesn't have the same you value as PIR insulation, but personally I would use Rockwall all day long if I could get to the correct U Valley so go for it
I'm doing a timber frame annex right now and am putting 65mm in the studwork and then later 65mm insulated plaster board inside. Do I need to be foam taping the studwork insulation considering there will be a second continuous layer?
Yes, everything you do correctly is definitely going to be better however as you know you are putting up another one over the inside so the choice is yours
Interesting thank you. Would you say with those poorly (but typically) fitted bits of PIR that it's better to leave a ~1cm gap round the edge so you can ensure the expanding foam runs all the way from front to back?
Even if you did that today, it's not recognises the correct thing to do. You're supposed to use this new tape that goes around the edges and expands it's called Gapo tape and he is very expensive
Just at @2:41 when you say there is a gap in the noggan, that is the wood to wood is it. Funny enough you can see a clear gap thin between the straight board and the straight wood. You say that when you are outside too. Crazy that it can’t be 100% no matter what. Is a new way of insulation install needed. Pushing boards into holes isnt great
Gapotape is great, made my diy job on an old victorian property much easier as it gives you a lot of tolerence. Way too expensive though so if more come on the market it will be great.
how can we do a partial thermal insulation of an old house if we want the thermal insulation work to be done gradually and partially, over the course of several years, having a low budget and living only in a small part of a house?
Yes I totally agree I'm trying to move away from all of this once I finish this side of demonstrating things I'm gonna start stripping back this demo rig and insulating organically definitely my preferred option
Hi, we moved into a bungalow that has no cavity wall insulation and the pointing is very bad. I wondered what your opinion on the best solution to insulate, renew the pointing then insulation in the cavity or external wall insulation?. Many thanks 👍
There's the debate on air gap versus no air gap - is there a consensus on this are you aware ? In my case i'm talking about insulating the floor from below with 100mm PIR against tongue and groove flooring. Thanks
Cost benefit calcs are the way to equate the efficiency of the extra work. This does mean shoddy work can be accepted and good fitting timber and insulation first round is a must. Now have a country full of incompetant and unprofessional builders and thats my experiance. I am not a builder but I am an mech engineer having used many diff builders. Roofers, id say 80% are pretty poor. This has led to some court cases. WhatbI also find is even getting detailed quotes of the work is near impossible and many just refusse to detail standards used and material/labour separate. The point here is hos is a home owner supposed to ensure high standards when the industry is just so bad.
Finding people with the skills to diagnose poorly insulated warm roof constructions seems to be almost impossible. I have an extension which is very cold and I'd love to be able to find someone who can tell me what can be done about it - I just can't find anyone!
Another great video Steve, I can see you put a lot into making this video. I saw Robin Clevit using this edging tape on one of his builds. My first thought was looks good but what's the cost. Hopefully prices will come down in the future.
Quick question if I may, I have a dormer with cheeks of 150mm so builder is using 150mm insulation between timber. Should I have more insulation over the top as well? He wants to use just plasterboard over
@@SteveRoofer the design said 100mm timber dormer cheeks but builder used 150mm. So it was a question of if the 150mm between timbers is enough or if should still overboard with more insulation to avoid cold bridging from the timbers
Well, yes, theoretically you should still put some insulation over the inside joists to stop thermal bridging, but if you've got no air then on the outside that is a problem in itself@@LaurieR100
Thank you so much for taking the time to reply. I love your videos, I’m checking it out with my thermal camera I think Im giving the builder sleepless nights!
I think we are getting a bit hung up on making things 100% air tight ect, it's the stuff of night mares, just do the very best you can otherwise you will never sleep worrying about heat escaping through pin holes youv'e missed and life's to short for that.
I don't like any of the solid insulations like kingspan ( Pir,s) because of the chemicals and gassing off so spray foam is a No NO in my book just not worth the risk
You will never get a perfect fit if you try cutting your foam to exact size. I always, purposely cut my foam around 70 mil. short and less wide. This leaves a gap of 35 mil. on all sides. The 35 mil. is a perfect size to properly fill with spay foam. I am sorry if I am being rude, but you don't know how to spray very well. When the gap is big enough, you can stick the nozzle of the spray gun deep enough to get to the other side of the gap...fill it to 50 to 60 % full (depending on the product..read the instructions) usually, a second pass is barely necessary.... cut off the excess.
In a construction of any kind, that should only be one vapour barrier, and that vapour barrier should be on the warm side of any insulation adding other vapour barriers can only just confuse the construction adding insulation that has foil on it in my view is not the correct thing to do, however seems to be the way the manufacturers and all building control except but it stands to reason you have one vapour barrier and everything else past that bath barrier must be of a lesser quality
Hi Steve when you put a vapour barrier under the cellutex. Say you used dpm where would you run it? Ie would condensation build up and then run down the polythean?
Firstly you can't use a damp proof membrane. All plastic vapour barriers are coloured green so you should be using a green plastic vapour barrier. If you insulates over the vapour barrier the vapour barrier will be warm and if it's warm you just won't get any condensation there this is why warmers are so good.
I don't think we will. I don't think it actually burns it sort of smoulders away but it's certainly not a very good material and it's very non-user-friendly and I think it's really bad for the environment
I’m a carpenter and currently constructing my partners gym. All timber construction.
Using the tape you have mentioned. Much prefer this method, it is time consuming but a better job.
Couple of things to mentions:
I do have a crown roof construction which adds to the overall outlay.
Cost. The tape cost as much as the pir insulation for the whole build.
Once you have a system going it can be quite quick to install tape.
All in all this method will have to become the norm as we evolve in the construction industry I just hope the tape price will come down.
Please send over some photos would be nice to have a look. Yes, its better but very costly. I think we will be moving away from PIR insulation soon I will be showing a completely different way of doing things in an up and coming video using mostly much cheaper insulation and a quicker method of installing also more air open!
@@SteveRoofer I will do Steve. Thanks. I have subscribed to you for some time and you have certainly made me re think on the installations of insulation products. You are a credit to UA-cam.
@@SteveRoofer looking forward to this Steve, informative as usual.
Yeh I would much prefer to use the tape but it's just way to expensive at the minute.
@@SteveRoofer Please do it soon - I am about to embark on a similar project.😀👍
In Finland we leave the foam insulation about 15 mm smaller on each side than the cavity and then fill the gap with flexible gun foam. That way we can ensure the gaps are filled entirely and no places for heat loss or air movement are left.
We usually also add another continous layer of pir-foam on the inside (normally 30-50mm). This layer acts as vapour barrier, insulation and thermal break all at the same time.
Se on juurikin näin! Olen myöskin yrittänyt opettaa näille miten ton tehdä , turhaan! Eihän niillä ole kunnon talveja jotta huomasivat eron.
@ Tämä. Välillä tuntuu, että pohjoismaiden ulkopuolella näissä asioissa ollaan ihan keskiajalla.
Thank you for the advice, having recently done a hot roof myself ( also tested with thermal imaging) i wondered what they would be looking for. This video explained it perfectly.
Glad it helped
Really appreciate this, spending your own time and effort to show us all this, very common mistakes like cutting the insulation board at an angle, i've heard that from many builders.
Glad it was helpful!
Its a hard job to get perfect cuts on thicker boards unless you have the perfect tools
Bear in mind this type of work in a lot of building projects is given to unskilled workers who don't understand or aren't shown how skillful work it is to try and get it right.
I'm rebuilding my old 1880s house and am using Rockwool/Rocksilk everywhere with a membrane. Cut it 1/2" - 1" bigger than the gap and it makes a nice tight fit and fills up any wonkiness in the battens.
Great video Steve, happy to collaborate with you anytime mate your passion and knowledge is an absolutely refreshing!!
Thanks unfortunately now I'm not on-site that much I'm not getting the opportunity to film what I need however going out and doing loads of roof surveys is enlightening as the misunderstanding in all aspects of the building trade is just astonishing. Love the job you are on now it's looking good. Yes if there is an opportunity I'm up for it.
Hey Robin, nice to read you in the comments. You are the one who tipped me to buy a Festool Insulation jigsaw (ISC 240)🙂
I think it’s important to be a little more clear on the definition of ‘loads of heat loss’ . As a previous comment mentions, what is the heat source used to record the heat transfer? Also what are the span parameter settings of the thermal camera. The images in thermal imaging can often look alarming but it’s important that the interpretation of those images is understood correctly to be realistic in the quantitive data. Thumbs up for the enthusiasm but those cameras in the wrong hands can be quite misleading.
Your absolutely right in aspects of your reply. My point in the video is we can do better and should do better.
In reference to the thermal camera, are you saying "please clearly define the colors in reference to how much of a change in temperature the areas are"? In other words, the visual "distance" between blue color on the camera and red is 0.5 degrees Celsius vs the "distance" between blue and red is 15 degrees Celsius?
Thank you, very interesting, the thermal images are superb for emphasising the issue of poorly installed insulation.
Glad you enjoyed it
The expanding foam absorbs moisture. This is why a thinner secondary layer of at least 25mm insulation over the studs is important as well as below the rafters. Even taping or sealing the external lining with another layer of insulation. We never use insulated plasterboard as you’ve then turned reflective insulation into convected insulation.
Although I can agree with some of your comments above I'm not quite sure about your comment on insulated plasterboard! By the time you've installed the plasterboard even if it's backed by insulation you are deemed to be internal and therefore you should have no problems.
@@SteveRoofer what about services coming through the wall ? Cables, pipes etc have to them penetrate the VCL for every socket switch pipe etc. every screw to install the plasterboard penetrates the VCL behind it. Here in Scotland we’re still 150 centres for fixing. That’s the equivalent of 19 penetrations from the face of the plasterboard into the substructure that we’re trying to prevent cold bridging from. The best way as we know to get rid of vapour is ventilation. There’s no ventilation next to either on the inside or outside face of a VCL that’s hard up against another surface. The other “issue” with insulated plasterboard is that it doesn’t prevent cold bridging from the substructure unless you’re able to seal all but joints between each sheet. And if you’ve got for instance a 72mm insulated sheet that’s probably worse than a steel penetration because it’s 72mm deep gap only stopped via the plaster or jointing compound.
Where as if 25mm+ of PIR is installed over the studs then battened out again all joints taped on the insulation to create your insulated envelope you know you’re now not relying on any other measure of sealant. Any penetrations in the future of the building will not affect the VCL performance. What about radiators also. On an insulated plasterboard wall with a foil layer directly behind the plasterboard it won’t reflect heat but absorb it as there is no airspace to reflect that heat into. Heating up the mechanical fixings also. Helping heat penetrated the insulation more.
It’s all little silly things but lots of little things can make that difference I believe. The least penetrations we can put in our walls where the VCL is involved, the better. No hundreds of staples. No hundreds of drywall screws, no multiple cables pipes or electrical boxes but into our insulation. Air circulation where you want it. Any moisture that may get behind a battened out wall over insulation has an air flow between the back of the plasterboard and the face of the foil. It’s also got somewhere to go. Directly down in the case of a malfunction. No need to seal plasterboard to floors etc. if anything you can raise it up 5 or so mm to help vent behind the board. It’s sure not detrimental to your sealed air. It seems a common practice though for big house builders to teach their workforce to air test after walls have been plastered. If we can air test at insulation level, we then know our insulation ins doing exactly what it is meant to be doing.
Just my opinion though.
Making a service void is alway the best option
@@SteveRoofer standard with us. Some councils won’t allow insulated PB when planning for extensions. I believe there’s an issue with fire ratings also.
Video, after video, after video. Always full of information and tips. Thank you for your effort!
Glad it was helpful!
Another brilliant video Steve, thanks for going to all the effort!
Very welcome
I appreciate there is clearly heat leaking through the badly sealed gaps between insulation and timber but it's a pretty small proportion of the wall as a whole. Surely the answer is to leave a ~10 gap all around and foam it. This would give a much more consistent foam installation and not only will this provide a better thermal performance through the foam - and the wall as a whole - but also, as you mention, much reduce air movement though it.
I’ve started using my table saw with an extractor to cut pir, it’s fast, clean and accurate. I thinking your using expanding foam you need to leave a 5mm gap all round to get the foam right in there, I’d be interested to see what works better- tight square cuts or loose cuts with foam around
Im going to do anther video and I will try that also i will compare the foam tape. thanks for the idea
Yeh whenever I foam in boards & I cut them with at least 5mm gap to get the foam in & use screws etc to hold the boards in place until the foam sets as fitting the boards tight sounds good but I always found you end up with some smalls gaps which you then struggle to fill because they are to small to foam properly.
@@SteveRoofer if putting that foam tape around every square of celotex is the only option it’s gonna make work so expensive we’ll be better of getting it sprayed.
Side note- I done a loft and garage conversion recently, foil taped the loft conversion, it cost me about £600 in labour/wages. Stapled a vapour barrier on garage conversion, cost about £80.
Yes its getting out of hand
Polyisocyurate PIR insulation is a cyanide based killer.all 70, Grenville tower folks died of cyanide poisoning in the fire fueled by this material. Tape the exposed edges and cover the lot with a vapour barrier to reduce heat loss but the inhabitants will be protected from the long-term exposure and lung damage this material will cause . Construction workers please use PP3 masks
Incredibly interesting and helpful ! Thank you so much !
Interesting video, with this in mind it may be an idea to change our construction so the installation can be installed without being cut, so maybe insulate in or outside the stud work
I think we will be moving away from PIR insulation soon I will be showing a completely different way of doing things in an up and coming video using mostly much cheaper insulation and a quicker method of installing also more air open!
@@SteveRoofer Intrigued to find out what pir can be replaced with!
Multi layer foil perhaps?
I just made my own tape. A roll of expansion joint foam and a roll of foil tape. Costs less than a quarter of gapotape and does the same job. Little bit more work tho.
I think something is going to have to change as at the moment there only seems to be one very small company making this tape
Can you post an example of the expansion joint foam…. I’m upgrading the insulation in my Dorma cottage… so far have just put insulated PB (72mm) over the top of existing PB (which has about 70mm of rock wool before the felt) I figured that because of the gaps PIR wouldn’t gain me enough to compensate for the mess of removing the rock wool and plasterboard… I am however going round with my thermal camera installing rock wool where there is none… However for the Apex I thought some PIR might help. Hence maybe using the quarter price gapotape….
Can you easily find wide expansion joint foam tape?
What an excellent video . Thanks for uploading
Steve, can you make a video on installing light fitting etc without damaging your vapour barrier? 😊
I run a layer over the joists. It solves the thermal bridging nicely
Yes thats the way to do it
Hello, What do you layer with?
@@ajaykumarsinghlondon 50mm PIR boards
The foil is not just a VB, but the performance of the PIR board is dependent upon foil facing either side. This also protects the insulation foam from decaying… this is probably why BC are asking for continuous foil. It all illustrates the reason for external continuous insulation.
Really good video showing the challenges, thank you.
Glad you liked it
Excellent information. Thanks.
I've been doing the second 50mm layer in my loft construction for years; no one told me; it is just common sense.
If you build with quality in your mind, all types of changes take place in your build.
The client pay more, but the end job and the economy in energy savings plus the comfort is noticeable.
Unfortunately not everybody thinks like that and a lot of jobs are just not finished off correctly
I installed 142 mm alufoil-faced insulation for my workshop build. The external sheeting was already completed, so I had real problems getting a precisely cut sheet into the stud gaps. Effectively, the sheet was compressing air. I found the most effective way to get a good seal was to cut the sheet exactly 10 mm too small, insert the sheet, then fill the gap with foam, starting from the back of the space. Of course, a workshop doesn’t have the insulation and damp requirements of a house, but I wonder wonder if my solution would be acceptable for habitable spaces. Final point, I bought the Festool specialist insulation saw. Used with their track it enabled extremely accurate and square cuts in the insulation. Disgracefully expensive though!
Now that you have everything hermetically sealed...the timber will rot out and black mold will proliferate. Homes need to breath.
Try looking up warm roof rotting problems in cold countries.
Well, if it's done incorrectly, you could be right, but what we try to teach here is how to do it correctly
Since the mockup is open, I''m interested on what you use on the inside to generate heat. I know it is not important, but it will give the whole story so the viewers (and me) don't have to think about that anymore.
I have worked for a company that does installation like this. Cutting the PIR insulation using a long Snap off Razor Knife and use expansion foam to close the gabs and tape the seams afterwards. The cuts will not have an 90-degree angle, the cuts will not be uniform.
That company never uses a vapor barrier. They trust the aluminum cover and tape to perform that function by itself.
As you tell and show, never expect to depend on one barrier by itself.
Using foam tape, this will help to have uniform insulation, but this means cutting the PIR plates using something other than these snap off razor blades.
Why do companies don't use better cutting equipment? Because it takes too much time, and time is money. This opens another discussion all together. Off course, the finished install that must perform as required and expected by the customer. The practical and the theoretical. It is difficult, especially retrofit installs.
MY QUESTION:
What will be the loss by not going for a correct installation?
1) Not having the correct 90 degree cut and correct size fit?
2) Not using foam tape?
3) No continuous vapor barrier?
I could argue, the best install would be closed cell spray foam. But that means, no DIY.
I see in the comments, you will show an alternative and better install using other(?) methods for the installation? I can't wait 🙂
I preheated the room with a fan heater for about an hour before taking a thermal imaging. I'm going to do some more testing with the insulated tape and see how that differs using the thermal imaging speak soon
Love your videos Steve. Would be interesting to see what the heat loss through those voids would be with 25mm pir on top off studwork and it being plasterboarded and maybe skimmed.
Great suggestion!
Any excellent presentation and an insight in the common day to day defects that are built into our buildings (not just homes) Unfortunately, over the years I have had to design and specify details that have tried to account for the general poor quality control on building sites rather than opting for the best performance. In this situation I would have specified multi-foil thermal barrier that can be purposely moulded around all of the elements and be easily taped with little or no damage to the integral vapour barrier. the speed of installation of the multi-foil offsets the perceived material cost premium so it can be cost effective and not only for heat loss. To add additional insulation in the form of PIR board on to the face of the studwork is easy and will be reliably jointed.
Whilst your video is very instructive, I wonder how much heat is really lost and whether this is just a storm in a teacup reaction? Having said that there is no excuse for poor quality control as the customer is not getting what they expect.
Yes the point of the video is to show that we can and should be doing better, i'm a lover of molty foil because of its ease of fitting, however I still see it fitted badly lights cut thoug it. Edges not taped and sweating problems.
@@SteveRoofer Unfortunately Steve, you are in the minority when it comes to good practice on building sites. There is little care given to installations for example, how many electricians actually understand that they are doing wrong when they cut through the vapour barrier or insulation? You shouldn't have to teach every trade what they should and shouldn't do in each instance but understanding the very basics and principles of general building should be on the radar of every trades person There are too many 'General Builders' who are single tradesmen and know little about the various aspects of building .
Why not use wool batts in the studwork then insulated platerboard over that?
+ use insulated plasterboard. on all perimeter walls. Just doing a big detached house with 75mm in the cavity with all joints taped with 100mm foil tape and 62/50mm insulated plasterboard on all perimeter walls and in reveals. 140mm in the floor and 100mm between the spar's. All sheet insulation cut at 355mm on a table saw using a special Japanese blade. Everything tight and sealed and overtaped Cavity block work completely OCD full fill, scraped clean and bucket handled, nothing proud . Should be toasty!
I wish the roofers I have met cared like you.
Thanks
Love to see you on a new build site, you'd turn inside out
So for a pitched roof is it better to put a membrane inside the room, then insulation behind that, and then OSB boards for the roof and a membrane on top of that, too?
EXACTLY the issues in our loft converstion - built by the builder who owned the place before us, but apparently didn't think insulation needed to fit edge to edge. Big gaps around the celotex, freezing air blowing though roof space so if it's freezing outside, the interior of the plasterboard is about 12C even with the heating on. The downlighters of course have NO insualtion above, so would be frozen if they weren't conducting heat out of the room so effectively. Cold roofs are a bloody stupid idea, since they're all installed so poorly. 😤🤷♂️
Yes, it's unfortunate all this detail takes a lot of time, but when you are trying to something like reducing the amount of lost energy from the building, then you have to be more precise, but for some unknown reason they can't seem to work this out
Use rockwool and will fit easy and nice. Then a vapor breathable barrier and is done.
Hello mate, sorry for being late.
Im thinking about igloos, and adobe mud houses and wattle and dorb and it strikes me that this method of construction here is doomed to fail in install. Why are we building the frame then stuffing the insulation on, when in the past the insulation was inherent to the structure? I like your video - and this is actually a pretty half decent install. Ive seen people just stuff boards in with no real care, spray, tape anything really, then slapping the dry wall on, or laying the brick before the site manager comes visiting.
I always say its like leaving your jacket unzipped in winter.
Would it not be better to just reinforce PIR in the process of pouring it, and use that to build with? Kind of like, concrete?
Thank you for doing this Steve. I have been retrofitting with PIR, using a tracksaw, to get accurate fits and it takes forever. I have an upcoming project so would be really interested in your proposed alternative to PIR.😀👍
Its on its way in about three weeks
Pir is just not the answer in older buildings in most scenarios as there is too much scope for poor detailing as insulation like pir wasn't designed into the building . Its great in a modern sips design.
Why dont you just cut the insulation 1cm narrower on each side and fill it up with foam?? No gap and full effect on insulation! Thats how i did and the house stays warm!
Everything you said is correct!
You seems you know the details.. I have sub question which i need confirmation.
When wee put bariers on both sides we basically trap air and humidity "between inside/outside space.
And people are screaming.. wood needs to breath and it will rot.. and that is never endless story.
Now these is my "logical guess" answer...
2 situations.. when we have new build and wood is not dray i would aggre with answer that wood needs to breath and prevent rotening and mold.. but in second situation when wood is 10 and 15 years old .. than it has stabilised and should not be problem with wood breathing or mold itc.. because it leaves in stabelised and unchanging enviroment.
What is your professional answer.
I side needs vapour barrier and outside will have a breather version so moisture can escape but not allow it back in.still need the air gap at the top for air flow. Seems to be lots of these videos coming out for now and don't know why
where does this vapour barrier go, stapled to the insulation before the plasterboard?
When I was looking into PIR foam panels being placed in a wooden frame like that, the Kingspan website said that it didn't actually meet any standards until you placed a PIR backed plasterboard across in the other direction, and from there I guess you would plaster/skim it and paint it making it a complete solution?
It's not your shadow in thermal imaging. It's a reflection.
Hello Steve, I’m a carpenter new to the UK from NZ where our insulation regs are a lot different. I’m doing my first build here for a client, and the original plan was a pitched roof extension with cold roof insulation. The pitched ceiling has now changed to a flat ceiling but still a pitched roof. Am I better off insulating the flat ceiling, or the pitched roof?
Hi Steve, stumbled across this video and very informative for understanding the importance of tight fitting insulation. You mentioned doing a test between three different installs, did you ever do that?
Most times we do 100mm between rafters then full sheets of 50mm pir over the top to prevent thermal bridging between the rafters. With that in mind what is the most effective way of doing it? To me gapotap seems insanely expensive, I've always fitted PIR very tight however I'm starting to think it might be better to leave 5mm all the way around and fill with a low expanding low u valued expanding foam ensuring it's the depth of the board. Do you have any experience with the best performing option?
I have heard good things about flexible wood fibre board insulation. Being flexible, may massively reduce this problem.
Yes, some of the new products are really good
Could really do with some advice unrelated to this video please, regarding felt corners . Thanks
email me info
@@SteveRoofer what's your email?
Hi , would it not be better to use multi layer foil on both sides and reduce the thickness of the slab insulation .?🤔
Yes that's an option
What that Gappo tape made from? The same precious gems as PIR?
It will cost a fortune to do it properly to building regs.
They are all in on it to rip us off.
Yes, but no movement of air is bad for wood. What next? Dry rot in stud walls?
I would be interested to know if multi layer foil is the not the simplest solution, no cuts, no gaps and no expensive tape. Use the foil as the first layer to "cover" the rafters/joists and then bulk up with whole sheets of rigid PIR and foil tape over the top if needed (depending on the efficiency of the foil I imagine)
Yes multifile is probably definitely the way to go
Excellent useful video. What is the model number of the thermal camera. Thank you
I have the use of meny thermal imaging cameras as my son is a level 2 Certified Infrared Thermographer some of the cameras I use are 15K plus the one I alway use is one you fit to an iphone costing about £300!
@@SteveRoofer Thank you
Useful.
Done well.
I used my flir m625 on top of a friends barn to see what was taking his chickens here in wisconsin.....well its 9' tall with 19" footprints... enough said
I would put another layer of kingspan/celotex around the inside, keeping a note of where the wood is under it with a marker pen at the edges, maybe sandwiching a plastic vapour barrier in between the 2 layers so it doesnt get damaged. But what of screw penetrations? There is a butyl tape which allegedly seals up. I got to the end of the video - you did anther layer like this. It says the 'next' video shows how to do the holes from the screws.... maybe a second layer of battens cross wise? Maybe I remembered it from seeing the video before! I'm going to do mine in Spring 2024. Maybe I'll make a video with my plans before I finalise so youtube can criticise and improve it ! I dont want the OSB and beams to rot after ten years from condensation !
sounds interesting get back to me if you need any help
Surly any insulation is better than none.
Yes that's one way of looking at it
@@SteveRoofer great video, well done.
Although it reduces the size of the room I always use 25mm of insulation board - cross boarding to finish off!
When i lived at home we had single glazed wooden windows, no central heating, no insulation in the loft or walls and just an open fire in the front room . But i never remember feeling cold or my parents complaining about being cold. Have we just become to soft?
Very helpful
Glad you think so!
With no stud being perfectly straight and cutting PIR perfectly also unlikely, surely rockwool is a better option for in between studs? PIR is a better insulator but the draughty gaps it leaves negate any benefit in my opinion. Plus it’s a lot more plastic for some poor sod to deal with later down the line
They insulated my bedroom and raised the ceiling. They never realized that it's a flat roof, It seems colder now than it did before they started. Will I ever have a warm bedroom?
Can we get video with tape instead of foam please just to compare both systems heat loss.
Thats a good idea ill get on to that
You simply lay a thin layer of PIR over the joists that acts as a vapour barrier and also reduces thermal bridging even more.
Just came across your UA-cam video here on insulation and wonder if you did a similar study on Rockwool rather than just Kingspan ? I am thinking of using Rockwool on my very old house where they added an extension without much insulation as it is also breathable ? Your video does highlight concerns about how well Kingspan fits into Joists etc.. and the gaps it leaves. I was also going to cover the insulation with a thermal/vapour barrier foil. Just wondering if tere is any specific qualities I should look for for the Foil ? Thank you for sharing your knowlegde about this as it if very imortant these days and people just don't seem to get it!
I'm a lover of rock wall as it is fair open problem is it doesn't have the same you value as PIR insulation, but personally I would use Rockwall all day long if I could get to the correct U Valley so go for it
The timber is the biggest cold bridge
Yes, that's why you should always put insulated plasterboard under a ceiling or internally on a stud wall
I'm doing a timber frame annex right now and am putting 65mm in the studwork and then later 65mm insulated plaster board inside. Do I need to be foam taping the studwork insulation considering there will be a second continuous layer?
Yes, everything you do correctly is definitely going to be better however as you know you are putting up another one over the inside so the choice is yours
@@SteveRoofer Yeah, the second inner insulation skin creates a full envelope. Thanks.
Interesting thank you. Would you say with those poorly (but typically) fitted bits of PIR that it's better to leave a ~1cm gap round the edge so you can ensure the expanding foam runs all the way from front to back?
Even if you did that today, it's not recognises the correct thing to do. You're supposed to use this new tape that goes around the edges and expands it's called Gapo tape and he is very expensive
No sack get someone how can cut proppley
Just at @2:41 when you say there is a gap in the noggan, that is the wood to wood is it. Funny enough you can see a clear gap thin between the straight board and the straight wood. You say that when you are outside too. Crazy that it can’t be 100% no matter what. Is a new way of insulation install needed. Pushing boards into holes isnt great
Gapotape is great, made my diy job on an old victorian property much easier as it gives you a lot of tolerence. Way too expensive though so if more come on the market it will be great.
Great point!
Agree, used it on insulating a loft knee wall area, makes fitting clean and tight. Good but pricey.
Do you know of a Gapotape alternative?
how can we do a partial thermal insulation of an old house if we want the thermal insulation work to be done gradually and partially, over the course of several years, having a low budget and living only in a small part of a house?
You do it with forethought, you will get there in the end
Is it really worth the effort?
Also, all that plastic... too much plastic nowadays!
Yes I totally agree I'm trying to move away from all of this once I finish this side of demonstrating things I'm gonna start stripping back this demo rig and insulating organically definitely my preferred option
Stuff carpet offcuts of different thickness or fiberglass insulation in the slots
Dumb question: What does the vapour barrier do?
Helps reduce the rising humidity in the rooms below into the roof void
Hi, we moved into a bungalow that has no cavity wall insulation and the pointing is very bad. I wondered what your opinion on the best solution to insulate, renew the pointing then insulation in the cavity or external wall insulation?.
Many thanks 👍
In your experience do you think this could lead to damp patches showing in the plaster . (Condensation? )
There's the debate on air gap versus no air gap - is there a consensus on this are you aware ? In my case i'm talking about insulating the floor from below with 100mm PIR against tongue and groove flooring. Thanks
Floors are totally different and dont need venting
Surely more is lost through glass no matter how thick ??
Getting a little bit silly if you asked me. Didn’t have any of this in the 90s. I was warm as toast. And dry
Cost benefit calcs are the way to equate the efficiency of the extra work. This does mean shoddy work can be accepted and good fitting timber and insulation first round is a must. Now have a country full of incompetant and unprofessional builders and thats my experiance. I am not a builder but I am an mech engineer having used many diff builders. Roofers, id say 80% are pretty poor. This has led to some court cases. WhatbI also find is even getting detailed quotes of the work is near impossible and many just refusse to detail standards used and material/labour separate. The point here is hos is a home owner supposed to ensure high standards when the industry is just so bad.
Basically some up the situation very well and trained and skilled people it's always gonna end in tears
Really good info thanks. Do you have a solution for services running though VB?
Yes form a void in front of the and rinsulationun all services in that
Finding people with the skills to diagnose poorly insulated warm roof constructions seems to be almost impossible. I have an extension which is very cold and I'd love to be able to find someone who can tell me what can be done about it - I just can't find anyone!
Try sending over some photographs by email
Another great video Steve, I can see you put a lot into making this video.
I saw Robin Clevit using this edging tape on one of his builds. My first thought was looks good but what's the cost. Hopefully prices will come down in the future.
Yes I watched that looks like a nice job he is doing a he has also commented below
Nice video thanks I didn't know this
No problem!
where are you buying your foam from? they're tucking you up mate. insta stick is only £13 from your builders merchant
yeah, I don't think I pay anything like that
Quick question if I may, I have a dormer with cheeks of 150mm so builder is using 150mm insulation between timber. Should I have more insulation over the top as well? He wants to use just plasterboard over
Yes, you should have an air gap on the outside and you should have the vapour barrier on the inside. You also should be following your design plans.
@@SteveRoofer the design said 100mm timber dormer cheeks but builder used 150mm. So it was a question of if the 150mm between timbers is enough or if should still overboard with more insulation to avoid cold bridging from the timbers
Well, yes, theoretically you should still put some insulation over the inside joists to stop thermal bridging, but if you've got no air then on the outside that is a problem in itself@@LaurieR100
Thank you so much for taking the time to reply. I love your videos, I’m checking it out with my thermal camera I think Im giving the builder sleepless nights!
I think we are getting a bit hung up on making things 100% air tight ect, it's the stuff of night mares, just do the very best you can otherwise you will never sleep worrying about heat escaping through pin holes youv'e missed and life's to short for that.
I agree t a point
so its ok to having 25mm kingspan between battens. the a vapour barrier on top. and then insulated plasterboard on top of that?
You will have to give me more details than that as I don't quite understand your buildup
@@SteveRoofer is it ok to have the vapour barrier between two sheets of insulation
Yes if u have 3\ 4 of the insulation above
Because the AVCL will not be complete it will have gaps where you cant join it
All ok for new builds and easy access. No good for retrofitting. And also the regs havent changed yet
You always have to keep in mind thermal bridging and air tightness, regardless of its new build or not
What do you think of the spray foam Insulation Steve?
I don't like any of the solid insulations like kingspan ( Pir,s) because of the chemicals and gassing off so spray foam is a No NO in my book just not worth the risk
Steve how do you know what vapour barrier you need ??
You will never get a perfect fit if you try cutting your foam to exact size. I always, purposely cut my foam around 70 mil. short and less wide. This leaves a gap of 35 mil. on all sides. The 35 mil. is a perfect size to properly fill with spay foam. I am sorry if I am being rude, but you don't know how to spray very well. When the gap is big enough, you can stick the nozzle of the spray gun deep enough to get to the other side of the gap...fill it to 50 to 60 % full (depending on the product..read the instructions) usually, a second pass is barely necessary.... cut off the excess.
Is it a good idea of having an extra layer of Vapour Barrier Waterproof Thermal Insulation Aluminium Foil Membrane
In a construction of any kind, that should only be one vapour barrier, and that vapour barrier should be on the warm side of any insulation adding other vapour barriers can only just confuse the construction adding insulation that has foil on it in my view is not the correct thing to do, however seems to be the way the manufacturers and all building control except but it stands to reason you have one vapour barrier and everything else past that bath barrier must be of a lesser quality
the timber is an issue anyway
Hi Steve when you put a vapour barrier under the cellutex. Say you used dpm where would you run it? Ie would condensation build up and then run down the polythean?
Firstly you can't use a damp proof membrane. All plastic vapour barriers are coloured green so you should be using a green plastic vapour barrier. If you insulates over the vapour barrier the vapour barrier will be warm and if it's warm you just won't get any condensation there this is why warmers are so good.
"thats why Warmers are good" ?
Warm roof ??
Board over it with a therm-backed board.
Im going to do that
Yes that is the way you are supposed to do it
Superb video as usual. Now stop teasing us with this future cheaper/quicker alternative to PIR & split the beans man!!! 😅
I have to finish doing all this rubbish with PIR first then I will show you where i'm going
@@SteveRoofer look forward to it 👍
We've gone pir mad, so many other options now.
Yes thats exactly my thoughts its like everybody using GRP is all salesmanship PIR is not good
@@SteveRoofer I Hate pir for lots of reasons. Caused so many issues. Also wonder what the effects will be on our health installing it too.
Have you seen that insulation burn? We will be pulling all that stuff out in a few years and putting in Glass fibre.
I don't think we will. I don't think it actually burns it sort of smoulders away but it's certainly not a very good material and it's very non-user-friendly and I think it's really bad for the environment
Like it very good info
Thanks for liking
Great vid, thanks for posting.
QUESTION - Doesn't the plaster & plaster board reduce air flow as well?
Maybe it's a subject for another video.
Yes it does however the better we start the better the end result