Unvented roofs - Closed cell vs Open cell Spray Foam Insulation which is better?

hello everyone mike with spray jones we're going to address a couple of questions and comments that i've gotten over the last little while about people saying well should we be putting close cell foam uh to the underside of the roof deck a non-vented versus open cell open cell is going to let the water through and if we have a leak wouldn't that be better and um i guess i haven't maybe i haven't really addressed this but this is going to be a specific video for it so if you want to bug out of here in under a minute the answer is going to be no you can put closed cell you can put open cell closed cell isn't going to cause any adverse effects all right now if you want to stick around uh after a minute's up and see why i'll back it up here with a little bit of some science and some engineering we have had all of our details done uh by morrison hirschfield which is a very large uh private building envelope engineering firm in canada and they they have done this on behalf of bsf so that they can have um specific but also generic type details that would be applied to any uh wood frame the building to answer questions about where spray foam can and can't go and they have huge credibility here in canada and they drew this drawing it shows right here uh four inches of wall tight spray foam this was drawn in 2008 being applied to the underside of roof deck and there's no ventilation whatsoever this is closed cell here's the double top plates of the outside wall insulation stop backer to keep it from going out into the soffits and then your slope pitch a roof and they stay here note four and five on the sheet so let's just go to where note four and five is at the beginning of the document okay here we are at the beginning and note four says applying wall tight to the underside of the roof sheeting unvented is only applicable to pitched roofs with shingles that are will allow drying to the exterior and then they say to check for warranty because they don't want to get into a a jam between you and the manufacturer on warranty which is a whole nother issue that i've i've already addressed shingle life shingle life and the unvented roof but let's just address this issue the water right why are they stating here that it needs to be to the underside of of a of a sloped pitched roof well i spoke to the engineer that wrote this i actually in 2008 was was having a conversation with him over many days and he told me that they have they feel comfortable with drawing this detail on anything that's 312 and up so three four five six on and on and on they have no problem issuing a generic detail that's not address specific so think about that for a second an engineering firm large with huge liability and let's go back to the picture that engineering firm is willing to draw this picture which says that four inches i don't care if it's four or if it's five i mean now it's now uh 2020 we're putting more foam in but it doesn't matter the the the the application is all the same the depth is a little bit more but the application is the same four inches of closed cell foam to the underside of a roof deck on a generic address non-address specific which means the liability options are huge so they must feel confident that if you're following this detail on anything 312 and greater you're not going to have issues and here's why let's say one of these shingles or a flashing is removed right where's the damage going to be located to only to the area where the water is coming in contact with if there's enough drainage it gets out and gone and is not going to be able to put it in a saturation situation long enough to cause damage elsewhere it will be only isolated to where the damage is now let's look on the on the flip side let's say that this was six or eight or ten inches of open cell foam if you put and lose a shingle the open cell foam is open cell it can act like a sponge it can hold a lot of that water so that means you're not guaranteed to see where it's leaking just because it's leaking here doesn't mean where the leak is above it can be leaking four or five two feet over to the left to the right in a totally different location it could be leaking for months before it reaches a high enough saturation to drip on the inside so you're not going to have paint damaged drywall damaged insulation damaged and then you still have to deal with the leak this is flawed logic now if you want to put open cell foam up go right ahead i'm not saying not to do it i'm just saying that that is not the silver bullet you can put closed cell when the when you want to pay for it and when you're in cold enough climates that you want to deal with something that's going to back up the roof give it additional snow load wind load structural support it's an all-in-one vapor barrier you don't want to be messing around with poly if you're in a climate that requires it if you're down in texas and you want to use open cell foam go right ahead i i have no problems with that but if you're in alaska or in canada and you want to use closed cell know that you can all right so saying that we're guaranteed to have a problem we're just going to hold water all over they make it sound as though it's just a matter of time until there's some moisture in here and we're going to rot out the whole entire roof deck and destroy the whole roof nothing could be further from the truth let's look at a few other pictures here's a good side elevation they're showing you conditioned attic space non-vented four inches of closed cell spray foam all the way down onto the outside plates referring that it needs to be uh shingled and pitched roof and i'd said three or four twelve greater so why would an engineering firm risk their liability risk being sued risk being uh putting out some sort of a detail there if the science wasn't behind it because the shingles are going to dry very very quickly the number one drying factor that you have on a roof is sunlight so if you're in a situation where you can get a decent amount of sunlight on the deck it will dry out moisture in a matter of hours especially in in a very hot climate if you've just had a heavy rain something's gotten wet but i've seen situations where these shingles have been lost windstorm tornado plow wind whatever's come through 100k you know 16 plus mile an hour winds come through ripped off shingles and the seams are left exposed now in a closed cell situation there's no immediate panic there's no meeting panic the water's not coming in through the seams it's not damaging the interior of the house the the closed cell foam is doing its job and keeping it out if it was open cell uh yeah you'd have an issue you'd need to get that thing waterproofed immediately so there's that advantage but it also works to supporting the deck taking out rafter twist a lot of times when the top rafter is extremely cold the bottom rafter is warm they're going to twist there's a temperature differential so the closed cell helps with that again if you want to use open cell i i really don't have an objection to that it's just you you are not doing wrong by putting closed cell up to the underside of the roof um i had a situation once this last story i'm gonna tell where a gentleman had a 12 12 pitch roof down the middle of his house 412 off to the side where the bedrooms were we spray foamed it and after 10 years he had to replace the shingles uh primarily on the north side in the shade side but he did it on the front and the back north and the south side in the valleys and the reason was he was getting an enormous amount of water coming off the 12 12 pitch and it was flowing underneath behind the shingles on the 412 pitch so it was getting the roof deck wet it was getting the shingle wet the shingle wrecked and he had to replace it and then so what they did was they took out that portion of shingles they cut the roof deck with a skill saw properly set to the right depth pulled it up because it was rotten anyhow because the water was getting to it the spray foam was fine the interior structure fine replace the spray foam with a do-it-yourself diy spray foam kit that you can get at lowe's or home depot or whatever shaved it off put the new plywood down put the ice and water shield on boom new shingles good to go so the this is not some uh tricky tricky thing the only thing that it's tricky to is people that don't understand the physics of what's going on and they subscribe to myths and they think well this is the way it's always been done and i i have a rule do not generalize from specific instances so or or reverse if you generalize and say hey there's there's there could be maybe there might be and then bring that into a specific instance and say well there might be a situation where we could have a possibility therefore never do it ever well that's wrong likewise if you had a very specific problem on a specific location because something was violated or not followed and then to generalize and say well we'll never do that ever again ever for anything is not correct either so the spray foam absolutely can be used close cell on the underside of the deck 412 pitch or greater just get the proper drainage have high quality shingles have high quality underlay and you're going to be fine get your your spray foam installer in your area your state your county wherever you are make sure they do an even inconsistent job that's why we want to see the foam to the deck and then from there you can visualize that everything is good long before the drywall is ever put up in fact you can even have a thermal imaging scan if you're in cold climate hot climate see how everything's performing and then you're you're good to go and um i i think the science is behind it i think the engineering is behind it if these guys didn't support it they wouldn't have drawn it this way and i mean you can comment and like and subscribe and share this with anybody you think this is going to be valuable to and we'll see we'll on you see you on the next one have a good day

Channel: Spray Jones

Views: 107,024

Rating: 4.9142365 out of 5

Keywords: Regina, 306, Walltite, Saskatchewan, SprayFoam, Homeinsulation, warmhome, homefoam, commercialfoam, betterinsulation, rightway, BASF, newsolutions, foamyourhome, nomorebatt, foammaster, sask, YQR, reginasprayfoam, sprayjones, bestinsulation, betterway, newway, foamit, newconstruction, commercialconstruction, ventornovent, atticventilation, nonventedroof, spfroof, sprayfoamroofing, hotattic, hotroofing, fiberglasssucks, wetbatts, wetglass, airleakage, badvapourbarrier, wetwalls, frostinwalls, gusmer, graco

Id: qB6-NUSPnHs

Length: 10min 15sec (615 seconds)

Published: Mon Aug 10 2020