Roof Decks, Water and Spray Foam Insulation
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- Опубліковано 23 тра 2022
- We cover water intrusion, possible damage, closed and open cell SPF, and what to do about it all when building.
www.sprayjones.com/
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Your voice, presentation and information are all stellar all of the time. Thank you for taking the time to post all of your videos.
You're very welcome!
Thank you so much for your videos and knowledge. You've helped me immensely with deciding to go with closed cell foam for my Texas home. So far I don't regret it.
Glad I could help!
Now I am retired and in Central Texas, but personally I would want closed cell, 100%, of the time and let me worry about the engineering and the roof. Great Show.
Suggestion - It would be nice to see a video of different types of rework, remodel or demo of previously spray foamed walls and roofs and what to avoid, not do, or make sure is done when a wall or roof that already has spray foam on it. Kind of an ok you have a spray foamed house and now years later you want to change something but here are some things you need to know to make sure you maintain the thermal, vapor barrier, and sealing effectiveness.
I had to do work in a renovation I had done years earlier. Ended up removing part of an exterior wall that had been spray foamed. Came apart easily, foam cuts out with a recip saw,no big deal. Had to remove foam on some walls to get to wiring. My spray foam contractor flashed those areas when he was on site to spray the new walls.
@@jonathanconway7256 Thanks, I was wondering if it would be a big hassle but it sounds like it's not.
thank you
I would watch it to the end.
Hey Mike thank you for all this info, I’m here for the nerdy stuff.
I’m in Texas and we are tasked with spraying retrofit with a vented attic with open cell foam.
What is the best way to seal a ridge vent?
The home owner plans on removing the vented roof in the future.
Informative. Thanks!
Glad it was helpful!
Good discussion. I am just designing a new build to be high-eff, or even net zero or passive, so I have been looking at the closed-cell spray foam a lot recently. Thanks for taking the time to explain all that. So these would be considered a "hot roof" if memory serves me correctly. Is there any consideration to the conditioned attic space that this creates? Does the HVAC design simply account for the additional space? Thanks.
Ok I'm convinced. Thanks for the informative videos. I would appreciate your opinion on something. I am building a large detached garage and now i am thinking having my contractor build a 2x6 wall with 24 inch stud spacing. I would also have them install a scissor truss style rafter. Then I would have someone like yourself spray foam the entire building with closed cell. Traditional dimensional asphalt shingle on the roof deck. Is there anything that you would do differently in this situation or am I taking a good approach here? I live in Alberta for reference.
Thanks for this! On a new build for myself, in US zone 5, I’m planning on an R15ish mineral wool on the topside of the zip roof deck, but I need to make R60 per the new codes. Would you see any issues doing a closed cell layer (3.5 inches) then an open cell on the underside of the roof deck?
Fan of your content here. Not a roofer but I understand that roofs are made to shed water, but are not "water proof".
Thank you for this, it answered a number of questions I had. I'm about to be remodeling my grandmother's hundred year old farm house, and I've been considering what kind of insulation to go with.
As I'm going to be doing a lot of the work myself (limited budget)- I know they sell the kits to diy this, but I'm wondering if this is the sort of thing it would be wiser to pay a pro? it seems kinda like it, but I'm interested in your opinion?
what about US termite companies excluding coverage for roofs that have closed cell SPF? Any suggestions?
Joe Listibruk at building science corporation has spent a career analyzing this and would agree with you. Indeed, he would argue for a diffusion vent at ridge line for the bulk of Vapor accumulating at the peak of roofs.
Am I screwed? My builder insisted on open cell spray foam for sealing the attic to make it a conditioned space. I wanted a conditioned attic. The walls are single floor of 2 by 6 framing with R-19 fiberglass insulation. The roof is a double layer synthetic underlayment with Certainteed Lankmark Architectural shingles. The roof pitch is 11-12. I live south central Alabama.
I dont agree with regards to a leaky roof being contained to a small area. Every drop that gets down to the decking will stay there and soak further and further since it will effectively be sandwhiched between two layers of non-permeable material [foam/shingles]. This will be much worse if the leak is occuring over where the decking lays on a rafter and theres a 1/32 gap for water to flow down. Even worse still if its happening over a sistered rafter thats been caulked on the underside creating a 1/16 water reservoir the length of the rafter. This obsolutely will cause structual damage if not detected quickly. Spray foam on roof decking can be great but the roofing system needs to be planned and prepared for it.
Very informative!! My brother is going to get a roof replaced and from what we think he might need to have his decking done again because code in the city has changed. right now he has common board on it as it is an older house. when they have to pull that to re-deck how is that going to work if he has spray foam on there?
Select areas that are damaged can be removed, I believe I spoke about this in the video.
If he wants to re deck the whole roof, he should strap it and place new decking over it. This is common and a good roofer will know about it.
Great video! As a builder in the north eastern part of the United States, I deal with new construction and close cell is the way to go for roofs. As I watched you video, a question came to mind regarding older homes. Can you tell me what additional weight is added to the roof deck from the closed cell? Here in New England there are countless home built 100 years ago when insulation wasn’t a consideration, and if insulation was added it was minimal and laid in the ceiling joists. Unfortunately roof rafters for these same homes might be 2x6’s 24” on center. Granted they do support themselves with a snow load, but if you add the closed cell to the roof deck does it create a load issue? I’m sure you would suggest seeking the expertise of an engineer, but I’m curious about the weight of closed cell once it’s cured, something never discussed with insulation contractors.
Under 1/2 lb per ft2.
What do you recommend to use Open or Close CellFoam for roof? Attic too hot even with the build in radiant barrier.
Closed
I had closed-cell sprayed in my attic in the underside of my roof. The mistake I made was not put new shingles on when I got this done. I do need to replace my shingles soon. Will the roofing job be difficult to do if no leaks occur till then??
No.
What happens if you need to replace the roof deck? Then you have to reinsulate with drywall installed already. Which would be a very difficult, and expensive, job.
I’m not sure if this has been answered in other videos, but is there a case for combining the two types of foams for roofs? Start with x amount of closed cell for the benefits mentioned and then switch to open cell for cost efficiency?
Choose one and stay with it.
Mike - Great content as always. I am starting to build an icf exterior wall house and plan to do a conditioned attic by having the underside of the roof deck spray foamed - solely because of your videos. There will be multiples sizes of top cords of roof trusses, not just 2x4. I understand the reasoning of spraying 4” to cover the traditional 2x4 but what would you recommend for the 2x6 and larger? I am in South Dakota otherwise I would have you do the work! Thank you for all that you do without asking anything in return.
Great question.
We build the amount of needed foam in between 2" x 6" top cords and allow only over spray to cover the rest of the lumber. To cover all the sides and top of all 2"x6" cords would add +25% more surface to the roof area in most cases. So they get a "skinning" as we call it.
@@SprayJones what happens if you need to replace shingles after foam installed?
@@ericwendel1258 shingles are installed on the outside on top of play wood so I don’t think that’s a problem.
Great videos, couple questions: we are using a 12” ibeam for the rafter.. to be a complete vapour barrier do you have to spray over all the wood or would spraying between beams would be good enough.. also what type of underlayment would you use for black shingles.. and would you still use ice shield? Thanks
We spray I beam truss frequently. Just build the foam up between them.
For roof underlay, ask your roofer. I do not make those technical decisions.
So you don’t need to skim completely around the ibeam? Just to confirm
@@megangoodyear4982 Completely around? No that will mess up everything. Just embed the 2"x4" top cord in foam and build up your thickness in the middle.
Curious if you think the prolonged exposure to the heat generated by asphalt shingles would degrade the foam sprayed on the deck.
No way. The foam can handle 180 F before it begins to degrade.
Is it ok to leave the ridge vent and intake soffits open when they spray foam under my roof?
No.
Do you leave the front door open all winter?
Watch the 4 part series on non-vented roofs to know more.
I here you keep saying closed cell , but on internet and here local in the south zone 7b people are say open cell. So do you still say closed cell the entire house ? Or just the roof ? does it even matter if it the property thickness ? Ok I think im sold on closed cell for roof, but what about walls?
It is a tool in the box. Use it when it suites you and the situation. Watch the 5 part series on now "let's learn SPF"
What makes spray foam pull down OSB, making the appearance of a wavy roof? Both houses were new construction.
I would start by looking at how thick the OSB was (7/16 or greater?), and if it was proper quality of grade.
Since 2020 there have been serious issues with OSB supply and quality. Many have switched back to plywood sheathing which is far superior.
I want to spray foam my roof rafters. However, thinking of getting a new roof in about 2 years. Should I wait for new roof to be installed before spraying?
That would be prudent, leave yourself with options to address the roof to 100% first, then install the envelope.
@@SprayJones thanks.
@@SprayJones We're in the process of renovating our previously renovated attic. Our attic was drywalled, it had blown-in insulation behind the knee wall and batt between the rafters. We're ripping everything out and are planning to re-insulate with closed cell under the roof between the rafters. Our roof has never been vented. The eaves are closed - no vent - would you also recommend applying sprayfoam on the floor of the attic at the eaves - it looks like it would be about 18" or so...
Also, and this is keeping me up at night - how much weight would closed cell sprayfoam add the the roof? I'm a little concerned about that because our home is a 1940's home with 2 x 6 rafters on a 2 x 4 stick-built home. the rafters are about 16' long on each side of the ridge beam at 24" on center... the entire roof is covered with asphalt shingles and I am pretty sure that there are 2 layers on there currently - the roof deck is made of 2 x 8 (true 2 x 8) and not OSB or plywood... so all that adds up with regard to weight.
Additionally.... the next time we do our roof, we plan to do a standing seam metal roof and we would be removing all the shingles (we'd have to anyway for code)...
My questions: 1) with our existing 2 x 8 roof deck and 2 x 6 rafters carrying 2 layers of asphalt shingles, would we be putting too much weight on our roof by adding 2lb closed cell sprayfoam instead of something like Rockwool - and 2) if we plan to re-do our roof in 3-5 years, would it be a mistake to sprayfoam now?
Thanks in advance for any guidance on the subject.
Most residential home roofing slopes are a 4 to 5/12, unless you are talking about homes that are in colder climates. And that's because of snow. The more the snow the higher you want your pitch so that it will be easier for the snow to e slid off
Yes.... the more money you have the more you want your roof to erect into the sky in order to compensate for other areas... We see a lot of that.
@@SprayJones I'm very impressed with your channel. I never knew that spray foam was that involved.....or complicated. I just started watching a week ago...but I've watched 15 or so videos now
@@dennisandrews8485 It is very complex. Thank you for the views. Glad I can help.
What happens if you need to replace shingles after spray foam applied? @sprayjones
He literally talks about that exact thing in the video…..but how and what would you do on a conventional attic if you need to replace shingles? The answer is the same.
I did talk about it in the video. Bang new shingles on...
any take on sprayfoam like this and metal roofs? will it help with sound proofing?
Yes it helps.
Open cell a much better sound deadening product, but as spray Jones notes, certainly not the product you want in northern climates, or even mid Atlantic temperate regions . And even in the south, while I believe open cell would be the product to use, I would add a diffusion type vent at roof peaks for insurance simple, cheap…
A diffusion type vent in the South? I thought those were only recommended in cold climates....@@johnwhite2576
Is there any scientific reason(s) for ridge rot for a roof spray foamed from the underside ? besides a roof leaking from the outside ?
The question is too broad to answer directly yes or no. What products used, what climate are they in, what conditions are a factor, etc.
I don't see closed cell as an issue.
I don’t recall if you highlighted this in the other series, but what specific precautions need to be taken if the entire attic and garage will be conditioned but there are front and back patios that aren’t? Does the osb blocking separating the two areas need any other specific care? This is assuming that the soffits will be vented for these patios.
You insulate what is to be kept conditioned. So where the roofs overhang you block them in at the house walls and close them off so that they are separate.
I live near Dallas and been unable to find anyone who does closed cell foam on roof decks, they all use open cell
Well.. either use what they sell or get someone to switch for you. Huntsman is right in Dallas... I was there in 2006 for training.
I was told the best foam sprayed under ideal condition with no voids was 5-6% open cell. That's 5-6% that can absorb water.
Watch my 4 part series on un vented roofs. explain it there.
@@SprayJones I don't understand how open cell is worse then close cell if both absorb water.
My brother and I own Bo’s insulation out of Oklahoma City, Oklahoma (USA). We now have documentation of all the energy consumption of 2 houses over the course of 2 years. The 1st house is 1500 square feet, built in 1964 with rockwool batts in the walls and blown in in the attic (vented system). The second house was built in 1953, is 1300 square foot and has rockwool in the attic but no insulation in the exterior walls. Both houses have single glaze windows and original hvac units.
We have a plan to rip off the Sheetrock and batts, suck out the old blown in from the attics, work hand in hand with an hvac specialist that’s keen on building science, spray the exterior walls and roof deck with closed cell spray foam, air seal with a spray applied caulking, run some blower door tests (potentially use aeroseal if we aren’t happy with the results), and lastly document the results of a FULL spray foam system and what it has to offer the modern world. My question to you Mr. Mike, would you like to help us with this? I just know that you could really help us make this worthwhile and lead, guide or direct us in the right way. You’re a legend in my book sir. We HAVE to show the world how unbelievable this stuff is (of course a true pro knows how to give the customer the unbelievable product of proper foam 😉).
Sounds interesting. I am not set up or insured to consult on work we are not doing. The results should be amazing, but we already know that they will be. It is getting the law makers to change the rules to accommodate the savings. Therein lies the real challenge.
@@SprayJones As it stands, utility companies hand out rebates like mad to get their insulation/windows/hvac upgraded. From my understanding, this is simply because it’s easier on that utility companies equipment when the house is more efficient and uses less energy. This enables the energy company to allocate the energy to a whole other property which is supposedly more profitable than having fewer less efficient properties. If this is all true, my plan is to show these utility companies the benefits of a proper foam system over to the older systems and see what happens from there. If these utility companies can dish out money to get their customers attics topped off with a few more inches of blown in, why on Gods green Earth would they not invest that money on spray foam. The only answer I can come up with for that is that they aren’t informed enough or they haven’t truly seen how much better it really is. You’re informing the world and I’m so grateful for it. Hopefully I can help make a dent as well. We may have to get creative but we have got to push the industry forward. It’s taking way too long for such a groundbreaking product to become the standard of building products in my opinion.
@@animedbz20 great stuff mate, much appreciated! Do you happen to know why they would give their customers an incentive to upgrade their energy consumption in the first place? What causes the energy company to want to pay for 1/4 of the cost to get their customers r-values brought back up to code? I would also like to not just sit and let the government take advantage of me if what you’re saying is true. If the technology is accessible to build a home healthier, more efficient and sustainable than ever before but we aren’t doing it because of monopolies and the government, I’m not here for it. Maybe a Steve Jobs of home health and energy will come about then the worlds energy standards will skyrocket in record time. Just like IBM had a monopoly with their technology and AT&T had their monopoly, it eventually came to an ugly head then humanity was finally able to move forward.
@@SprayJones you said we already know that the results will be amazing and you’re absolutely right about that. My only disagreement with that statement is that it should be changed to the PROS know that the results will be amazing. People spend thousands on cars, clothes and iPhones all day long but breathe in their own farts because they’re unaware of modern day home efficiency. The average consumer is just buying a house and the builder is just contracting out the next contractor. If we can somehow change how the world thinks about this, we could be the next Steve Jobs of “home health/home energy”😂. You’d be absolutely amazed at how far behind Oklahoma USA is in the insulation and home energy/health department. It’s incredibly embarrassing.
Underlayment has always been required by code in the USA. Underlayment is not a secondary water barrier. How could it be with four nails per shingle. Only ice and water shield is a secondary barrier. Foam insulation applied to the underside of the roof deck sheathing voids most glass reinforced asphalt shingle warranties.
And the primary issue with spry foam applied to the underside of the roof desk sheathing is vapor drive to the exterior. if this moisture laden air reaches the wood structure there is no way for the wetted components to dry. in an assembly where air can freely flow over the surface of the structure it can dry down and the chance of decay is reduced.
I have been involved in countless projects where spray foam is applied directly to the underside of roof deck sheathing and the sheathing and structure are decayed to the point of collapse as a result of moisture drive to the exterior. why did the condition go unnoticed til collapse you might ask...liquid water was never noticed at the interior of the structure a real problem with spray foam
Wrap up spray foam has its place in construction. the underside of any roof deck is not the place.
If you want continuous insulation at the roof deck place it over the roof deck sheathing. Provide a vent space over the rigid insulation and install the roof of your choosing. Place the vapor barrier as dictated by your region.
Costs are comparable to spray foam and you will be much happier
Consult a building envelope expert with accreditation when building any dwelling for best practice
Close cell foam will eventually soak up water believe me we used to use it in our boats, why do you think Boston whalers every year they sag deeper deeper in the water cause of water soaking into the foam , now that’s just my experience with close cell foam in boats
Closed cell foam in buildings will not soak up water. They are not in constant contact with the water. Comparing it to use in a boat is no where legit for buildings.
We have the SPF approved for in contact with ground for under slab and exterior of concrete. I have SPF applied for 1/2 mile of inground water piping.