Unvented roofs - Closed cell vs Open cell Spray Foam Insulation which is better?
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- เผยแพร่เมื่อ 16 มิ.ย. 2024
- Many people want to know should they be placing closed cell spray foam up against the roof deck of a house, shop, barn, loft or some type of wood-framed shingled roof.
Well we get at that subject and hammer is down in 10 mins.
www.sprayjones.com/
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Love how you gave the quick answer, and then gave the support… this respects the watcher and allows us to determine what we want or need to watch. Greasy job. And great job on the supporting video.
Thank you.
True. Except, sometimes it might be a matter of whether they want to hear it or not. :D
Glad to have that question answered. That made sense. Thanks
Glad to help
Great video - thanks! Good to have solid info like this....Ive had many discussions/arguments over exactly this! I Had Closed cell sprayed in my attic roof deck and walls - in a 100 yr old wood stick frame house. It tightened everything up and Ive never had a problem since. It has paid for itself on my heat bills over 4 years.
Thanks for sharing!
Top shelf educational vid ... thanks again for these thorough vids and explanations
Thank you for making this video. Exactly what I needed.
I love your videos man, especially this one. Straight to the point to those with a low attention span and want a direct "yes or no" but then a full technical explanation. Keep up the awesome job!
Thanks
Excellent video and format, thank you
Yup, we had a large portion of our hallway ceiling collapse because the cellulose took on so much water, then the plaster soaked up so much water. It ever so slightly dropped over the years of the leak and one day just collapsed. The weight of the plaster was incredible.
I retrofitted my 90 year old home with closed cell foam under the roof sheathing. There was effectively no air sealing or insulation there before.
My natural gas usage dropped 50% in December in Ottawa.
This video is making me even more confident.
This is a question I've had for since I decided to go spray foam. Thanks.
Glad I could help!
Exactly the evidence.. Information i was looking for. Thank you
Will look into it more
Glad it was helpful!
A so true statement just because it is leaking in one place that does not mean that is the origin of the leak.
I have watched 20 videos and asked about 10 questions. I am finishing my 2nd floor cape in MA with a 12/12 roof with closed cell insulation ONLY. Rest of the house is open cell. I feel 100percent confident that its the right thing to do. I dont know what it will cost but it doesnt matter. I am looking forward to a great envelope protecting me from summer heat and winter cold.
Sounds great!
Man what an awesome vid and explanation. All any of us want are common sense answers backed by rational data.
Amen.
What an amazing explanation!
Glad you think so!
We have open cell sprayed on the underside of the roof deck, It was done in 1998. The roofer did a poor job and many nails missed. These small leaks were not big enough to drip below, but big enough we noticed soft spots in the decking. Rather than take the roof off and deal with the soft decking we instead nailed 1x4" perlins through the shingles and put on a metal roof. There is now a one inch air gap between the original roof and the metal. Not only did this solve the leaks but the house is noticeably cooler in the summer. We are in Indiana so summers are very hot.
Good testimony that shows it is NOT the end of the world for a few leaks. People make out like the roof leaking inside the house will limit the damage.
I have seen 5 layers of shingles on one roof.
After 50years Renovations. You see a lot.
Old timers theory was if it leaks and you covered it up to solve the problem. You are only fooling yourself.
The moisture is still in there. Stupid thing like capillary draw and physics-based tell you that if the problem is eliminated then it is solved.
My former 20 year apprentices ousted to have a saying from his grandfather.
"No one can afford to do it right the first time. But they can always afford to do it right the second time. ( after they ripped off what they did the first time after it failed)
Best overview on the topic..thx😊
Glad it was helpful!
I really appreciate your approach to these videos. Concise, thoughtful and informative!
After running a renovations business for a little more than 20 years now, I find myself building small-ish cabins for use as long term rentals as well as to sell. Looking to keep my costs low, I have looked to an idea that I used about 12 years ago on my own house build with a semi-vaulted roof system. (Scissor trusses) To obtain the required R value in the heels of the trusses, I was forced to use spray foam. After weighing the costs, I ended up using two layers of 4 inch blue Polystyrene foam insulation attached with quick -forming adhesive and recessed about an inch from the sides of the trusses cavities. Then, I filled those gaps with spray foam and added (approximately) 2 more inches of spray foam over top of everything.
The Polystyrene boards were acquired from another job (re-doing a metal flat tar roof on a Home Depot building) so it saved me some serious $$.
I too thought that insulating the roof deck would be advantageous over insulating the ceiling, and it has been maintenance free ever since.
I was concerned that the minimal contact of the Polystyrene to the roof deck would be an issue, but it has been fine. Roof is a 4/12 with tar paper underlayment and 3 tab asphalt shingles in Edmonton Alberta. Any thoughts on this?
Love your channel - liked and sub'd!😊
The principals are all the same, except you have a tough job trying to repeat what we are. Self-adhering rigid insulation, and conforming to the irregularities of the space created.
Much depends on your diligence to get it well adhered and sealed. Air sealed is the major.
@@SprayJones agreed. I'm always looking to save $$ where I can, but the long term savings of a solidly insulated (open vaulted) roof system far outweigh the higher initial costs. I will do more research for current standards in my BC here, but I remember having to convince the building inspector that the spray foam on the roof deck option was a good and proper way of achieving required insulative values in the roof structure.
I don’t know why I can’t stop watching your dam videos.
They are blessed, not damned... Lol
Great vid, very helpful. I'm embarking on a closed cell job for my roof deck. Two quesitons if I may!
1.) Is adding stregth to roofdecks for snowload a universal benefit when applying at least 4" of closed cell?
2.) We just completed some sistered rafters to the attic roofdeck. New lumber to old rafters. Should the new lumber be dried to a minimum moisture before spraying foam?
Absolutely. Matt Risinger utube supports very similar procedure.
And we can watch this video without seeing skinny jeans.
I've seen Matt Risinger spew some extraordinary amount of stupid at times... Just sayin.
Unfortunately where I live in the south termites are absolutely out of control and you don't find the damage until it's far too late. I have open cell foam and all of my house, but dearly regretted given the circumstances
I guess you can add that closed cell is IRC code required in the United States for any unvented attic where the spray foam is applied to the underside of the roof deck.
Wow, I love your video. Only problem is that I saw it too late. We just had our roof replaced with aluminum shingles. The underside of our roof sheeting is insulated using closed cell spray foam. The Installer claimed that he could not put the Aluminum Shingles directly on our existing plywood. He took off our old shingles and weather barrier and add a false roof over our 12/12 sloped roof. And in doing so he neglected to raise the flashing around our cultured stone chimney. As a consequence, to his actions, we now have water entering our home where the closed ends at the lower edge of our roof. My question is could aluminum shingles (which vent extremely well) be placed over a roof that has been spray foamed?
Thanks very educational
You are welcome
I know this video is two years ago but I am just getting into the spray foam world. Had lots of people talk about needing to install some sort of roof baffles or some sort of ventilation. From watching this video it appears that that is not the case, correct. Spraying UPC 2.0 foam, living in Palmer Alaska. Thanks!
Watch the vaulted ceiling playlist. There are a lot of videos there to get educated on.
Leaks are tricky even at best if circumstances. Our house had a roof leak for years but we didn’t known because the cellulose absorbed it until it become a huge leak.
Fiberglass loose fill 7:21 will let water through quickly.
I’ve been using 12/12 and 10/12 pitches for years. We use closed cell foam on our new builds AND we use Huber Wood Zip roofing and Ice guard 4’ up and high quality underlayment. The chances of roof sheathing damage is very very low.
Now, could damage occur one day if the future home owner don’t take time to visually inspect their shingles? Yep. But then concrete and steel eventually erode from neglect also.
I’d the price of closed cell foam was 1/2 it’s current price, I would ALWAYS use it to make our attic spaces un-vented and all our walls and rim joists sprayed over with 3” of
Closed cell and then the balance dense pack fiberglass we use 2x12 rafters and floor joists.
Here is some facts. Energy prices are going to quadruple as the “greenie religion” forces everyone to use electricity only. Better to pay for insulation and air sealing today. Payback isn’t going to be all that many years.
@bret9741 Solar with batteries is now the cheapest way to produce electricity.
Here is a great video comparing coal, gas, wind, and solar.
m.th-cam.com/video/6_BGHy4sfMs/w-d-xo.html
Your videos have helped convince me that an unvented condition attic is the way to go. We are going to put new asphalt shingles on just prior to spraying closed cell foam on the rafters. What kind of underpayment should we use?
That is your roofer. I do not know.
Pick the BEST SPF contract you can. Vet them out and do not be afraid to pay for it. Less issue potential.
Great info, earned a sub from me. Really like that you give an answer right away then go into details for the rest of the video. Joseph Lstiburek does some great videos that go along with what your saying. Keep up the great content
Thanks for the sub!
Great video! Just the info I needed. One question: see any issues using zip system roof deck and closed cell under?
Not at all. But get some pros in your corner when making final decisions. Ones that understand foam and not old ways.
Good stuff man!
Thanks for the visit
Man I love your Channel.
Great information right to the point and I can tell with alot of experience. Thanks
I appreciate that!
Thanks for your videos, great information without the bs.
For sure.
Just found your channel. Good info. Somethings to mention. Closed cell in this scenario needs to be air tight with no air leaks through to roof sheeting. In my experience, air leaks in cold climates can drive enough moisture to cause structural damage from rot. Also ice dams can be an issue. We've had good luck with using baffles to create 2"+ ventilation space and thus maintain a cold roof while still gaining the advantages of closed cell foam, the added rigidity, the conditioned attic space, much less ice damming and, for me, accessible ceiling systems.
The baffle idea seems like common sense to me and to the installer I've used on multiple jobs but I've never seen it mentioned in any foam industry info. Wonder why?
Do not agree.
@@SprayJones his point seemed logical I wonder why you did not agree. Could you please explain, thanks so much. Also if you have an air gap there if you had to replace any sheathing, it would not interfere with the spray foam.
@@davidhannan2023 The air gap is a fine way to hybridize ventilation while remaining sealed. Engineering tests have been done on this. Google Search: BA-1409: Field Testing Unvented Roofs with Asphalt Shingles in Cold and Hot-Humid Climates
The hybrid method with the air gap between the foam and the roof is what I am going to do on my new roof since I have to replace ALL of it, and I'd rather keep my roof cold in the winter, so it doesn't get assistance melting from inside.
I would assume that now the space is not unvented anymore. This video is for unvented spaces so everthing needs to be ar tight.@davidhannan2023
Thanks for the video. We just closed on a house in the Seattle area (Marine 4) and our roof is going to be replaced along with some of the sheathing (mold). We need to fix the insulation to help keep condensation out and was considering going closed cell foam so we can use the attic for conditioned storage. How does CCF on the rafters do in the wet environment?
I was reading in your comments that vents would be better to not be there. Our alternative is to replace, seal and blow in to R40ish to keep the moisture down, but also read that over venting in the Marine 4 environment will actually cause more condensation. I just want to do the best practice and hopefully avoid these issues.
We have a lot more moisture than Regina plus we have 2 skylights that I am worried about the low R causing condensation in the winter.
Please watch my 4 part series on nonvented roofs. All of your questions will be covered in detail in that learning session.
That was fantastic. WELL done. Subb'd
Thanks for the sub!
Have you ever spray foamed gambrel roofs? Would like a video in that maybe talking about pros and cons
Great information. Thx:)
Glad it was helpful!
Awesome
Videos you’re doing your community a great service thank you! Question- when you talk about the case with the man with the 12/12 pitch going to the 4/12 and water getting underneath the shingles… why would they have had to apply more spray foam when doing the repair? Wouldn’t the old closed cell foam remain undamaged and flat against roof deck so that the new piece could simply been placed flush right over it?
They chewed up the foam when they did the repair. Common issue really.
Amazing videos, I'm building my new home and was hesitant to go with spray foam due to sketchy contractors. I wanted to hire you so bad for my job but it looks like your in Regina SK. I'm in Calgary AB is there anyone here you know that is as great as you?
Call BASF Canada and ask them to get you in touch with Steven Cole. He is the Walltite rep for Western Canada. He can then vouch for proper installers that spray the foam in your area.1-800-891-0671
Watched numerous videos of yours you are destined as you said to do this.
looks like you do great work I've been trying to figure out how to re-insulate my home in Maine which the fiberglass has failed and mice have gotten into it and everything you can imagine because of the roof venting.
I'm going to continue studying your method as philosophy and by next summer should have a good plan to re-insulate with foam.
I'm wondering if you can recommend any certified companies in Central Maine that could do as good a work as you do on my house ?
Thank you for your feedback it is a welcomed change from the "experts" who chime in their critiques.
You will have to open things up, remove and clean and then proceed with foam. I cannot recommend anyone in that state. I get asked this weekly now.... who I can recommend for all over the USA and Canada.
Try Maine Passive House Bethel Maine
Question. Is there an advantage to 1" of closed cell followed with 3" of open cell? As opposed to only 2" of closed cell? Some installers are recommending this application mainly due to cost of material. THANKS!
Can you use 2" of closed cell then fill gap with open cell? I have an I.C.F home basement, and 2nd floor 3rd floor is a mix of 2"x12" walls and 2"x6 walls ,I'm going to have a condition attic that is cathedral type , the contractor I'm looking to use is recommending open cell with the thought that a void in the 2"x12" wall area and possibly the 2"x6" wall will create a bad echo ??
Thank you for your videos! I enjoy learning from you! Would this also apply to a metal pole building? I want to have the walls and inside roof metal sprayed with closed cell foam, but I am concerned about ventilation. This building will eventually have heat, but no A/C. Do you have a video already on this situation that I may have missed? Thanks for your assistance!
This is an older video, so you may not get a response from the author.
I am preparing to build a house and have done much research into spray foam.
If you use closed cell spray foam, make sure to get enough thickness to prevent condensation. Some climates an inch will work and some climates might need 3 inches.
On a metal post and beam construction make sure you have an experienced spray foam guy do the job, if it is applied in to thick of layers it can cause some deformation in the longer open spans.
I found this vid because I am spray foaming the roof deck on my build.
@@charlesarmstrong3536 Thank you sir! Much appreciated!
Can anyone explain the e84 rating and what iS difference between class A? Also Mr. Jones if you read this would you think a 2x4 exterior walls wills 1 inch of foam on outside (zipr system) then spray cc foam 1-2 inches then fill with wet spray cellulose.
Also using cc fosm to underside of roof sheeting. My big concern is fire and spreading quickly. Is E 84 rated cc foam a good choice?
Thanks for any help.
Peel and stick the sheathing to seal all the nail holes and control moisture intrusion. Spray a drainage coat before the foam.
Can you use close cell on 1/12 pitch metal PBR roofs.( in south east US)
Have perused your vids but can't find anything spacific. Thanks for your ethics's just wish ALL spray foam contractors had your integrity and desire to educate others.
As for as I'm concerned that is what transparency is meant for.
I think you made a good case @7:30 for not using closed cell foam. Once you encase the roof deck in closed cell you would have no way of knowing if your roof is rotting away until your shingles start to fly off. Sounds like cutting the roof deck with a skilsaw might have been avoided if the leak was detected early.
I like the idea of open cell for that application, closed cell everywhere else.
Just ask a roofer how many times do they have to replace roof sheathing on a conventional roof when they replace shingles? How did the guy in the story I told discover the issue?
The key is if the roofing allows trapped moisture to get out. I would assume most asphalt shingle assemblies will but not nessarily.
If you do have a leak in your roof with spray foam on the underside you will not know it until the sheething, structure has rotted away. As stated, that foam glues everything together, it will be very difficult to replace that. Given that roofing guys often have to replace sheets when re-roofing houses, I would be very nervous putting spray foam on the underside of that decking.
Saying that, there certainly are lot of advantages in spraying the underside.
Google search: BSI-016: Ping Pong Water and The Chemical Engineer
Open-cell is a disaster waiting to happen. Just read the study from that search.
You are an awesome tuber, THANK you for getting to the point strait off, for those who just want tje answer you did us a huge service. Ill subscribe for that
Wow! Right on. Thanks
We have to have some type of ventilation in attic spaces by code in Michigan. Mechanical or passive ventilation your choice. With proper ventilation your shingles will last longer and not blister up. I have seen house's roof sheeting rot from spray foam and no roof ventilation. Currently ripping out finished spray foam basement. They sealed the masonry. Masonry loves to wick moisture. Condensation built up in blocks over time. Till it leaked in basement. The masonry needed an area above grade to dry moisture out. With roofs the issue is condensation. I tell people to make sure they have roof vent baffles installed before spraying foam.
Watch the video I made on shingle life and SPF.
Then the 4 part series on non-vented roofs.
Code is based on open cell fibrous NOT SPF. So you cannot import misaligned rules to this system.
We live in Alabama and are building a new house. We are considering open cell foam. We have an old gas stove, a gas dryer, a gas water heater and want a ventless fireplace. Is this contraindicated in foam houses?
You address a shingle application, what are your thoughts about a steel roof at 3/12 with closed cell? Thanks
Hello Mike / Spray Jones,
Thanks a lot for the collection of very informative videos. This video regarding closed cell on unvented roof assemblies is very clear. The only question that I have from it is whether you feel this applies to ZIP roof sheathing ? My research leads me to understand that whilst ZIP roof sheathing is waterproof, it is vapor open and as such, moisture could become trapped in the OSB of the ZIP boards, between the foam and the face material on the boards. I have been recommended to install rafter trays underneath to allow for air flow to deal with this. Have you worked specifically with ZIP or could you consider a video specific to this installation method ?
Thanks again for the really well put together videos - I know how long it takes to make all this content !
Are talking about inside or outside for these vents?
Inside, on the underside of the zip roof sheathing. If you would do it differently, I would be very interested in your opinion, or a future video on this application.
@@jamesmiller9177 The roof has to be watertight to the outside. That is: fasteners, underlay and flashing. That is the roof's scope and the primary water defense for the life of the structure.
The SPF on the inside is direct to deck with NO ventilation. Closed cell does this the best. This is an INTERIOR envelope issue. The fact that insulate sheathing is used enhances the fact that internal vents are not needed.
INTERNAL venting is for air leakage water to find it's way out. Not deal with water intrusion from the exterior.
I will go into amplified pontification about this when I make the vaulted roof series.
Thanks a lot for your input on this. There is a lot of misinformation out there on spray foam and appropriate application which this channel tackles really well. I look forward to more on this in the upcoming roof video(s) !
I would assume a roof with lower than a 3 pitch would have EPDM or greater roof covering and would allow for the same /similar detail.
It would be the same. Vulcanized roofing over the top.
The other safety factor is to install roof wrap. On the roof. Usually a water repellent membrane. Before the shingles are applied.
Great video. I Have my spray foam contractor and he is recommending 8 inch open cell for my 2/12 pitch sealed cathedral roof. What do u think. I live in Lafayette Indiana so we have all 4 seasons. This room addition is considered a four season room so a lot of windows. Will use water shield on entire roof with fiberglass shingles
I am indifferent. If the climate is warm enough open cell is more than OK.
Great video.. I never understood the logic behind people saying open cell would be helpful in the event of a leak.
Me neither
What about a flat roof with modified bitumen torch down roofing? When they're talking about three and twelve they're specifically referring to using shingles, right...?
Should I spray foam my flat roof? Its 2x6 joist with existing shingles
My neighbour just had open cell foam installed - I'm located west coast Scotland very wet, damp, humid conditions most of the year, wettest and windiest place in Europe... Closed cell sounds better to me... Can you tell me about off gassing with open and closed cell please, you seem to know your stuff, thank you in advance.
Your videos are extremely helpful great job
What is the foam you are using? I have not seen the purple stuff except on your channel
I,m in Northern Minnesota and plane on using close cell in the whole cabin would this be a problem?
Thank You
Closed cell is exactly what you should be spraying it with. We are using BASF's Walltite. You will not see that in the USA because it is blended for Canada and has to be dyed purple to identify it for the building code here.
@@SprayJones
thanks for the quick reply
Hey Mike! Appreciate all the info in your videos. We are currently building out in BC with ICF. What would the insulation detail be for 2:12 sloped and flat roofs with closed cell to the underside of the roof deck? Any special requirements? Thank you!
I do not consult on projects I am not being hired to spray. Talk with the people you intend to hire and they should be providing that data to you. If they can't that's a red flag.
@@SprayJones 10-4 Mike. Thanks again for all the great content!
things change over time do they still maintain the same stance? 2008 is a long time ago..
Wish you were in Toronto! I have added an addition to my double car garage making it tandem on one side so three vehicles on the ground. Furthermore, 16 ft high for additional storage. The roof slopes to a flat roof. So I'm safe to spray foam the sloped portion but what about the flat roof portion. All quotes received recommend r31 5" closed cell. Thoughts? Is spray foaming the underside of a flat roof safe?????
Yes spraying a flat roof can be safe as long as certain conditions are met. We have done many. Are you saying that the roof of the new addition is 5" spec?
First thanks for the time you spend on the video's - I'm thinking of having some put on the plain underside of the garage roof in ontario. I imagine that some drying occurs towards the inside and I hear about solar drive pushing that. Am I just overestimating the amount of drying to the inside and the loss of drying will just happen to the outside now? Or when there is snow on the roof for 3 months solid? Thanks for the insight
The number 1 way a roof dries is via sunlight to the OUTSIDE. Does this help you?
@@SprayJones - Yeah I figured that. I was just thinking about what happens to the small amount that previously dried to the inside.
I seen metal buildings with flat roofs which spray in foam insulation if I built a metal building I would do this spray in Foam and insulation and I would cover it all up with metal It's a metal roof if you can't find a hole in a metal roof you do not belong on that roof please comment back if I am right or wrong thank you I used to do roofing for many years burn down rubber roofs Hot roofing jobs And also shingle jobs I used to find the holes in the hot roofs and the burn down rubber roughs before I found the shingle week a less it was a single missing or just a natural HOL E in The Roof or a less it was in the valleys or around distinct pipes or around the chimney every so many years you're supposed to go up there with a bucket of gunk and re do them thank you for this video
Half way through my remodel i decided to swtich to nonvented attic with spray foam.
I have a metal roof no penetrations. The plumbing vent goes out the siding near the peak then up above the roof line per code.
If i did it again i would have used zip tape over the rafters to protect from nail holes. I also would have used zip roof deck. Im not a pro builder but i do think things through.
Fortunately i used a metal standing seam roof instead of shingles so my decking ahould stay dry.
What about 4:12 or greater invented metal roof with high heat peel
And stick underpayment as a roof
In Florida.
Was looking at 2”closed cell
I'm planning on building a metal building home, all metal structure and metal roof, in Louisiana. It is a 2 story home with the entire roof inside vaulted and will be open to the inside of the house. I plan on using 2-3 inches of closed cell, sprayed directly to the metal, on the outside walls and 3-4 inches and the roof. I live 3 miles from the coast and we get lots of rain and sometimes flooding. I'm wondering about mold issues if we end up with standing water inside the house. Will mold grow on the foam? My other questions is the metal roof, what if I get a leak, how would I be able to find it or is this even a concern on metal roof with closed cell sprayed directly to it? I love your videos, they are very informative!
Mold will not grow on closed cell foam. Mold needs an organic surface to grow on.
can i get paperwork on the closed cell, want to put it in my house, need it for my Building permit
We recently completed a 12/12 pitched roof with the axis east and west for future solar. Direct southern exposure and the plans specified closed cell foam on the underside - no ventilation.
I've been doing this for almost 50 years and the thought of a cathedral roof with no 1" continuous ventilation from soffitt to ridge vent used to be heresy, but now is the preferred method.
I have been in many an attic that is suffocating in the summer heat, and the old 3 tab roofs would literally curl up at the edges like bacon and then a stiff wind would bend them up and over at the next edge. My concern is what roofing can stand up to the south sun with an insulting layer under that allows no heat dissipation? You mentioned 'ice and water' as the underlayment and the specs did note the roofing material needed to be approved for this application. I'm in Seattle, so not so cold and not so hot, but plenty of water.
In addition, our building inspector mentioned the dew point as the main factor in negating the need for ventilation. I have a roof interior coming up for insulating and want to be convinced that this has stood the test of time and I'm just ignorant.
In the 80's we went thru a period of maximum building wrap, sealed windows, caulking everywhere and vapor barrier on the inside, but the exterior envelopes leaked, the insulated walls could not breathe and there were whole blocks of apt buildings requiring residing in less than 10 years. It was a major problem up and down the west coast from Canada to California.
I subscribed and am working my way thru your videos...Thanks for all the info. I know this is part of your marketing but I also know when someone loves their job.
Richard go to the playlist on this channel dedicated the vaulted ceilings. Watch the 4 part series on non vented roofs and the shingle life video I did. That should quell any normal concerns.
I put closed cell up 20 years ago on vaulted roof around 1.5 inches never had any condensation i can say for sure because much of it is unfinished to this day I'm in Chicago area. Before i put up any foam I waited for some heavy rains to make sure no leaks. If I were to do it over again I would use ice and water dam from bottom to top. I did have a woodpecker make a hole in the wall one sheet of OSB damaged about 2 feet by 4 feet spot to fix and I scraped the OSB off the closed cell foam without damage to foam. This foam won't hurt any shingles.
@@portagepete1 thanks for the vote in favor,
my wife wonders what takes me so long to decide...but I just watched a pros and cons (mostly cons), and the #1 issue was flame retardants (mandatory). Any bad smells allergic reactions,..cancer ?
What about open cell for the underside of an EPDM flat roof? I assume this means the roof assembly needs to dry to the inside during all seasons which requires proper HVAC maintaining low RH in the dwelling.
We treat EPDM flat roofs on a case by case basis to review all variables and liabilities. In short we have sprayed all that we have done with closed cell because it was the right fit for the inside.
Closed cell on the bottom. Peel and stick or fluid applied on the top you I’m pretty sure you will NEVER have a problem. Thoughts?
Agreed.
People that have issues have chosen cheap products, installed by morons, because of the bottom dollar was good.
I have a cathedral type home with a Cupalo in the Panhandle of Florida and I am considering this method. My question is how does the moisture inside my home escape through the closed cell to the atmosphere? Especially if CC foam(as I understand ) is a moisture barrier. Thanks for any help
Please watch the 4 part series on non-vented roofs. Your questions are answered there.
Great information! What are your thoughts to use either foam type on a house that has a 12' overhang covered deck that uses the same roof line (same slope no transition) that has Ice damming with heavy snow loads? I would need 1,300 LF of heat cable to try to bandaid the problem.
insulation under the shingles in the area that is ice damming is unlikely to solve the problem.
There is not enough heat at the roofing to keep the melted snow liquid and it refreezes. This is what causes ice dams. That is why someone is recommending the heat cable.
Getting a local roofer familiar with this kind of issue will get you the best result.
@@fhuber7507 thanks for the response, I actually completely removed blow and all bats, repaired baffles, installed 3" R-Tech/air sealed (everything.), installed batting and finished with blow to a minimum R-60 (attic access was insulated to R-60 using pink foam board and pressed tight to also air leak). I moved all roof penetrations vents to the south facing part of the roof and eliminated a skylight on the north facing side. Moving the vents required me to use 4" foam core PVC ducting to not impact venting due to the additional distance, these pipes were then insulated to a minimum of R-30 near the roof penetrations. I build a cat walk over all of the insulation so I can access areas that may require service (vent penetrations, exhaust fans). I installed a roof exhaust fan (GAF), an articulating camera, and a light that all can be powered via WiFi so I can monitor conditions in the attic. I also installed a wireless camera on the roof so I can see when this roof has snow on it, so I can turn on the exhaust fan. It was an extremely difficult and labor intensive project that took me years to get the knowledge to put it together, but it works, the snow this year in Central Washington has been record breaking and there is no ice damming whatsoever (no need to have the snow shoveled and electric bill is much lower on this property).
I was extremely thorough as I wanted to avoid using heat cables as they seem to be a dangerous band aid. I will be looking to do this on another property this year, minus the 3" foam board (ridiculous amount of work). Thanks
@spray Johns - I’m from Arizona in the US. I currently am renovating my entire 1976 ranch style house as we had a audit and I have a R6 ! Our 1700 house with 2 people has a $450 power bill and very uncomfortable house :/ ...Do you have any info on adding foam to exterior brick ? How well does it work ? And lastly does that insulation and closed cell foam throughout the house really save 30-50% on energy ?
You need to gut the walls from the inside. Then the old insulation is removed, and the foam can be installed. This is a disruption to your life so make it count. Do as much as you can. Maybe the whole place from inside....? Yes the foam will save massively. You are about to have your mind blown!
Building Science Insights: To Vent or Not to Vent watch this he is an authority
Good Info, but would you spray closed cell directly to the underside of metal roofing (ribbed steel panels) like in a Pole Barn House?
Yes. We have may times. Go watch the Pole Shed video we have made. Aug. of 2019.
Would a standing seam metal roof further decrease the potential leaking consideration?
Over shingles? Sure, but all things come down to installation excellence.
What is the R value of that purple foam in this video?
So if closed cell was applied, I’m guessing you wouldn’t use any iceshield beneath the shingles? I can see the inspector challenging this lol. At the same time, although I completely agree with your argument, one would never really know when there’s a breach in the osb sheeting, beneath the shingles.
What you do exterior is not much of my concern. I see no reason not to use the ice-shield, it changes nothing for the envelope on the inside.
@@SprayJones I wonder, though, could you have a problem with water seeping through the plywood to the bottom and have no where to go and get trapped top and bottom, or should you use an ice shield but leave some less water tight area at the very bottom in the eaves?
Thoughts on renovation application to a 100 year old plank deck with multiple questionable or moldy areas underside? The drawings seem to apply to new construction with no reference to old homes and integration of vintage and modern practices. Plank spaces knot holes and other openings and less than new kiln dried lumber would seem to pose problems. Sealing in 100 year old low slope 2 x 4 roof and rafters as well. IN those cases would a plywood or other baffle base be warranted to provide ventilation and drying space from underside as low slope roofing does not allow drying from the exterior. I would like to see these legacy home issues addressed directly.
Well....... working on that now.
Friday will be brick old buildings and foam. Lots to go over there.
I am currently doing the companion video for it on old wood homes.
Your answer is already spoken in video #3 of the 4 part series on roofs and SPF. Listen about why we vent inside in the first place....
Fix the questionable areas and then have closed cell SPF installed from the inside.
The rest... you will have to watch....no spoilers.
I’m in SoCal, so a fairly temperate climate, and have a garage I want to insulate. It’s all open hip roof, with no venting. Problem is the roof decking is 6” plank boards, not tongue and groove and noticeable gaps. The closed cell spray foam at first looks like a good solution but I’ve seen elsewhere problems with cheap and/or unauthorized shingles for spray foam underneath. Should I stick with foam board instead?
No, SPF is the way.
Watch the 4 part series on roofs to know more...
What do you do for a pitch less than 4/12?
I am planning a pole barn that I want to enclose and the roof pitch is closer to 2/12. The roof and exterior will be steel and unvented.
Thank you.
Steel you spray it just the same.
We do all pitched 1/12 and up.
can you link the study on the shingle temps? I remember a video but I dont think there was any links to the info.
I have them in PDF format. I don't know if you can find them easily anymore.
If you like, email me through my web site and I can share them with you.
Can I ask thoughts on pole barn metal siding roof house wrap and roof vapor barrier under metal. Can I foam the entire building non vented. And closed cell on walls but a few different sprayers in my area say different for the roof line some say closed some say open building will be heated building is in PA
When we speak non-vented we mean no vents bringing air between the SPF and the exterior. The foam is applied direct to roof deck.
I do not like ANYTHING between the foam and the roof when doing this method.
I have a 4 part series on roofs, attics, vaults and SPF. Huge info to come.
I have a newly constructed, wood post and truss, 2500 sq. ft, 30 foot tall farm pole barn in Colorado, with metal siding and roofing. Foil faced bubble wrap between the metal and trusses/walls. Foam-style vented ridge cap. I plan to closed cell foam the interior walls and ceiling, and heat the building. Do I spray foam the foam-vented ridge cap??? Thank you
You do if you are going non-vented SPF to the deck. The venting is to bring air into an attic space.
You need to carefully detail this out with your installed. WHy? Because you have another layer that the foam is to adhere to. So confirmation needs to done.
What are your thoughts on using a peel and stick for the entire roof deck (for a metal roof) and closed cell on the underside of the roof deck? Would that trap moisture and prevent the sheathing from drying out on either side?
Great stuff!
Need a diffusion open membrane. It is simple to source and have installed.
Why use ice-shield on the whole deck in this situation? You can't have ice-dams anyway in winter. And if the metal is done right you won't have a major rain leak. Just use a quality underlayment (not asphalt).
@@SprayJones could you provide an example of this style membrane please?
That's exactly how I built my home on the Gulf Coast, (Hurricanes) ICF with metal roof with peel n' stick and closed cell on the underside of the roof deck.
@@CougarLand Because the ICE Shield does not blow off in a Hurricane.
I believe one important Building Code detail... as Part 9 of the NBC is being cited... you don’t mention is the requirement for a vented air space between the top of the insulation and the underside of the roof sheathing. I’m not saying SPF cannot be installed in this location.
However, since no vented air space is being provided and most jurisdictions (Cities) must follow the prescriptive Acceptable Solutions listed in their Provincial Building Code, the use of an Alternative Solution may be required.
I highly suggest the local Building Inspector is consulted before SPF is installed to determine if an Alternative Solution will be required.
You are correct. For the last 12 years this has bee placed to bed. The Province reviewed this and has approved it. You have to apply with your SPF paper work at the time of permit and then it will be granted. There aren't too may places that have an issue with this.
I live in north Europe and have a 30 degree angled roof with roof tiles on top, then a non-permeable plastic layer, and inch of foam and than and than a 1,5 inch thick layer of osb below it. My understanding is that closed cell foam spayed from underneath to the osb would create a moisture problem as it could dry out, therefore is it correct to say that open cell foam would be the better option?
Please watch some of my other videos on vaulted roofs, including the one on shingle life. Foam to the roof deck when properly installed does not create an issue. Provided other weather-proofing measures are taken.
They said it needs to be able to dry to the outside. Does that mean there are situations where you can’t do a mental roof and spray foam?
I keep hearing conflicting info on putting foam directly to a roof deck. Some people insist you need an airspace there to keep the roof deck cool.
You do not. Commercial roofing does not use an air space between a deck pan, rigid and a top membrane.
It's time to break out of 75 year old technology and the dogmas that go along with it.
True !
I had multiple spray foam installers (got three quotes) tell me it was fine. My roofers wanted vents, I told them I was spraying to the roof deck - they checked with the shingle manufacturer to ensure they would be able to offer a warranty before they even started on the roof (wasn't a problem). I then checked with my Hydro rep (when I was having my house assessed for energy efficiency grants) and he stated that a vented roof would actually lead to more problems and the only reason that it's still sometimes done is because building code is lagging behind the technology. Same reason the spray foam guys actually told me there was no point in spraying more than 4" of foam on a roof or 3" in a wall but code may still require it because it's based on fibre glass batt R value (or did when I had my house sprayed and inspected). As a result they had to spray 4" on my basement walls to pass inspection even though they said there was negligible returns going from 3" to 4" on a wall. My only concern was the point brought up earlier, that if there was damage to the roof you would never know about it because the water would take a long time to go around the foam to get into the house and show itself. That's where investing in a proper roof comes in - get the membrane, get the ice and water, get a company that does it right.
Can you do a couple layers of Closed Cell Spray foam as the vapor barrier and finish up with 2 or 3 layers of Open Cell Foam
Only if someone has the stats on that to prove it out.
Generally yes.
Thanks for the video. I live near Amelia Island Florida. Hot, humid summers and mild winters. House has a vented attic with flexible ducts…(maybe R8)
AC works very hard in summer to satisfy 77 degrees Fahrenheit.
Is it possible to have spray foam installed in a finished home that has a vented attic. Roof is a 6/12 pitch with trusses. Would you use open cell or closed cell if it is possible? Do you have a company in the Jacksonville area that you could recommend?
No to spraying retro fit when tight. I do have a video on spraying inside enclosed attics, there is not enough room to do the job properly.
My builder said he only sprays open cell because of yrs of experience with both. He's had way more issues, both short and long term, with closed cell. I do know I have leaks and have no clue where the source is. My house stays a consistent temp yr round and my electric/gas bill stays relatively cheap compared to my old house and other people I talk to. My attic is unvented conditioned with 4" of open cell foam.
Sounds to me like your builder has issues with trades... having leaks will wreck anything over enough time.
what would be the purpase of spray foaming under the roof decking if you have a flat ceiling home ? would you still insulate over the ceiling ? otherwise you are paying to heat and cool your attic space. i understand on a vaulted ceiling.
1. They owners don't want fibrous and all it's issues.
2. They want the support and weather proofing layer
Go Watch the playlist I have on "SPF for vaulted ceilings" many of your questions and objections are answered there.
Your reference stated shingles. Are there objections to roof steel directly to the roof deck with closed cell? Or are perlins required?
I am not following you on you install ideas. Purlins are a structural question not a thermal envelope one.
How about a barn pitch shed Metal roof in Oklahoma.. what would you recommend??? Thank you
Closed cell.
Can closed sprayfoam be sprayed in the attic under roof here in phoeniz az 🇺🇸 ?we run around 115 degrees here in summer
Yes.
I noticed that you sprayed the complete 2x4 even on the bottom for the ceiling. Does this need to be done in order to make it all vapor proof? I am having my addition spray foamed with the following. Rafters are 2x12" 12" on center. 3" closed up to the roof deck then an additional 4.5" of open cell. So this leaves the bottom of the 2x12 not sealed. Should a plastic vapor barrier be installed. Have not talked to the contractor about this yet. Project site is in central Massachusetts
You have some technical questions that need answering. Talk with your contractor.
Closed cell foam is a vapor barrier.
Can roof sheathing dry upward when covered by Ice&Water shield and standard shingles?
We are spraying the underside of our 4/12 pitched roof in NY, where we have all 4 season as well as low and high humidity
Yes it can if vapor-open membrane is used. Your roof can answer what their products can and cannot do.
I live in the south and have an older house. I have a ridge vent and side draft exits, do those stay? Can i also leave the blown in insulation that's already there on the floor? Would you recommend closed cell?
I live in AZ and also wonder if I used closed cell do I need to remove existing blown in insulation and block off my attic vents. Also do you need to have the attic ventilated with your hvac also
Just wondering what you guys ended up doing? I have a similar situation. Thanks