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spoofer
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# Posted: 7 Apr 2014 08:44pm
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Can I liguid nails foam insulation directly to my osx plywood ceiling. My roof on top is stick on snow and ice. I don't use the camp much, but the ceiling sweats without any in the winter. the builder never measured the rafters gap so it varies from rafter to rafter.
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MtnDon
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# Posted: 7 Apr 2014 09:02pm
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Many adhesives are not foam friendly. Check the tube for what materials it can be used with. It should state foam can be used otherwise there is the risk of the adhesive dissolving the foam. I know Loctite makes a couple that are foam safe. They have 2 polyurethane adhesives that are foam safe IIRC. It helps them cure if you lightly mist the wood with water as the foam is glued to the wood. You will need to prop the foam tightly against the sheathing until the sdhesive cures. About 24 hours for the Loctite. You could also try the liquid polyurethanes adhesives like Gorilla Glue. Also water mist. GG cures faster than the Loctites.
Keep in mind the bond to the foam is only as strong as the foam. If the foam is on the underside that should work okay. FYI, foam is quite flammable and building codes require it to be covered by something with a fire rating equivalent to 1/2" sheetrock.
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spoofer
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# Posted: 8 Apr 2014 08:23am
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OK then. Foam dosen't sound like the way to go. Any recommendations? Remember rolled fiberglass mats won't work.
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TheCabinCalls
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# Posted: 8 Apr 2014 12:56pm
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Foam is fine. You can use silicone, spray foam or something that won't eat the rigid foam. Friction will also help to hold.
How will you finish this inside? Knowing that will help decide what to you to install.
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spoofer
Member
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# Posted: 8 Apr 2014 09:43pm
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It's a Rustic cabin. I'm just looking for the best way and cheapest to insulate it. I would probably paint the foam white to brighten things up.
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Just
Member
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# Posted: 8 Apr 2014 09:59pm
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Foam should be covered with something fire resistant !!! ie. drywall
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MtnDon
Member
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# Posted: 8 Apr 2014 10:03pm
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Rigid sheet foam cut to rough size, close enough to be a friction fit in a few spots is most likely the best to use as most everything elese will absorb water vapor. Then use foam in a can to seal the edges. Then the question is how to cover it to make it fire safe.  The easiest thing would be to use 4 x 8 panels of something, but there goes your rustic look.
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TheCabinCalls
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# Posted: 9 Apr 2014 09:15am
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Thinking outside the box here (literally). To keep that look inside that you have going, is it possible to insulate the outside or attic.
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spoofer
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# Posted: 9 Apr 2014 10:15am
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That is the front room of the cabin. I am actually insulating the back room. The rafter situation is the same. I just don't have a picture of it. There is no attic. It is in this order. Rolled roofing over osx particle board, held up by rafters, that are not spaced equally apart.
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creeky
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# Posted: 18 Apr 2014 05:07pm
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that is rustic. looks great.
you could cut in polyiso foil covered foam sheet and then paint that. Maybe put up a 4x4 sheet of some metal sheeting on the rafters where it's over the stove. with that pipe probably a good idea anyway. that'd fit. oh wait. it's the back room. well. never mind then.
for the foam sheets: trimmed roughly to fit. couple dabs of silicon to hold em up while you spray foam the edges to lock it in place. then paint. There is fire resistant foam spray.
I did something similar with my studio. I trimmed my foamed edges with a knife afterwards to make them look more uniform. each to their own.
it's not code. but. cough cough.
HOWEVER
One problem I see is trapping moisture between the roof liner and the foam. That osx could go pretty quick if it gets and stays wet.
still. that's guessing that the moisture comes from the humidity in the room and is condensing against the cold ceiling. at least foil covered iso is a vapour barrier. So well sealed? An experiment.
AND
I'd probably think about foam sheet insulation on top of the osx/water snow layer. then putting purlins over top screwed into the roof. hopefully hitting rafters. and then put a metal roof over that.
it would be way easier than trimming sheets around rafters. foaming. painting. No fire problems. And you end up with a better roof.
what climate are you in? that'll tell you how much insulation to use.
that'll be .02 $ please.
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spoofer
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# Posted: 18 Apr 2014 10:26pm
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Im in Northern NY. Lots of cold and snow. I just put a new roof on the camp and raised the pitch. Im going to buy the foam with the foil on one side, and cut that to fit and staple it up. Should the foil face downward to deflect the heat?
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creeky
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# Posted: 19 Apr 2014 05:06pm
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foil down. better vapour seal.
there are 3 kinds of foam. polyisocyanate comes foiled. xps doesn't but is vapour/water proof. and styrene, which comes foiled. you'll need more styrene. maybe 6"? 4" of xps wouldn't hurt you either. and 1"xps roof side with 2" of polyiso on the room side (or 2" xps, 1" foil iso). All will insulate your ceiling to 4 season category.
for northern ny your shooting for R20. but pick yer comfort level.
watch web/newspaper for sheet insulation left over from bigger jobs/recycled cheap. xps basically lasts until the sun explodes. polyiso is pretty good too, i think it's better kept dry and on the warm side for best results.
i don't know a lot about styrene. apparently it gets better r value wize with colder temps.
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spoofer
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# Posted: 19 Apr 2014 07:55pm
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Im just looking to put an inch in or so. I have nothing now, so that would really help my r value. Only use it a couple of times in the winter. Thank god for cheap wood and stoves in Northern NY
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ErinsMom
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# Posted: 21 Apr 2014 07:18pm
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A novice here, could you use duravent then insulation?
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