Getting R-30 in an attic suite with 2x6 ceiling rafters

hi guys this is Dave again I don't know if I told you my name in the first one Dave this episode is talking about insulation because where I live you have to have to pass inspection r30 insulation now if you have to buy six rafters which a lot of us most of us almost all of us in this area have it's impossible to get our 30 unless you pat out your rafters down to like 10 inches and if you do that then you've got no space left so they recommend you go in and you spray foam it or whatever well if you're doing it yourself you're obviously probably not able to afford spray foam so that's out of the question so this is the poor man's way to get our thirty and two by six joists this is the insulation I'm working with this is two-inch polyurethane foam insulation with a fiber facing I guess it's called so this has like paper in it and fiberglass and I will tell you yes it does have fiberglass this is tortured to cut and work with you got to cover every square inch of your body and you end up et and your hands are burning and just gets all over and stays with you a couple of days each one of these boards 2 inches thick is roughly our 11.4 I think yes 1 inch is 5.7 so 2 inches is 11.4 so to get our 30 you have to have at least three layers of this stuff so three layers will be six inches deep well I have 2 by 6 rafters as most of us do down here they're already installed half this insulation I wanted to do this video before it was all installed so you can see how to seal it in all and most shingles actually require ventilation and the ventilation is pretty standard is one and a half inches between the insulation and the roof decking itself so the way you get that spacers one and a half inches this is just by ripping down if you can see this ripping down a nice order to buy stock which is actually one and a half inches put a little bit of liquid nails on the back of these spacers and I just spaced them out like two or three feet and then once you do that then you have your spacing that holds two layers a foam away from it so you can put a layer foam layer foam and it comes flush our third layer of insulation is almost in I'm gonna take a moment right now to show you how we fastened it it was right across the ceiling rafters lengthwise and we fastened it with some really long three-inch three and a quarter inch plus panhead type screws with one-inch washers then we come back in and fill in these little gaps with some phone so you see all that dust in the air that's what it looks like now nothing is you that's what it looks like when you're cutting there smoking cut this stuff really easily with a handsaw hold mag 77 skill saw to cut most of it cuts like butter but creates a huge mess just an example of the debris everywhere little bits of some of that is straight on but it's just oh all right oh no I just realized this one I was gonna say now I've gone back and got all three layers of insulation installed and then we're ready to get back in foam you can see how we work around these top plates cut around all the collar ties up here this is the bathroom shower very careful fitment and then we're gonna come back in and foam all these cracks everywhere all the gaps with great stuff or some other polyurethane foam variant but let's go back and put that one last piece in there and I just vacuumed bad young all the joints sealed all the collar ties sealed round all the studs all this delicate work and this bathroom I had to piece all this together because it's so tight got everything sealed up see I even went back in and sealed up here behind so you can see the the gap going up in there so that is one and a half inches all the way from the soffits down there it won't focus just a little too dark in here it's been creep it down down that works all the way up to the ridge way up in there and then we thaw everything in here so the moist air that comes up from the soffits doesn't go up under the insulation in any way shape or form it just goes straight up behind this insulation all the way to the ridge vent up there now we got left to do is throw some r30 bats across here before you throw in the drywall and some r-13 bats in there and it cost about $1200 for all of that foam board versus four to six thousand for spray foam thanks for watching

Channel: DIY Dave

Views: 1,411,180

Keywords: 2x6, rafters, r-30, code, attic, polyisocyanurate, suite, sloped, ceiling, carlisle syntec, polyiso, gaf, roof, foam, board, rigid

Id: 44dPWgoxhXw

Length: 7min 22sec (442 seconds)

Published: Wed Nov 14 2018