adding vapour barrier and r value to existing home

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adding vapour barrier and r value to existing home

Post by kurt333 » Mon Feb 11, 2019 4:29 pm

Hey Shannon,
I noticed in my attic ceiling insulation, it has that old gyproc brand insulation, paper backed on both side, stapled in place, green lettering that says gyproc. I then have pink insulation over top of that, I think its R20 or 2x6 insulation. I will have to measure it again the thickness.
But what do you guys think the R value on that old paper backed insulation is?
And of biggest concern to me, There is no vapor barrier when I look under the insulation in the attic bottom layer of original insulation. The paper backed stuff is not everywhere and is ripped and damaged and done in some spots. I would like to throw it all away and insulate with another layer of pink new stuff. But then how will I make a vapor barrier and or what would happen if I have no vapor barrier in the ceiling? Am I throwing away heat?
Also my walls are old gyproc insulation, paper backed both sides, 2x4 walls. Would I gain alot or keep heat in if I shimmed my walls out and 2x6 insulation the outer walls? I also have no plastic vapor barrier on the walls right now.
I think I want to start with my attic by re insulating that to bring it to R40 or so hey. That would probably be my best and first area to concentrate on hey.

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Re: Main Vent Stack ABS Pipe Sweating Moisture Buildup-Insulate?

Post by Shannon » Mon Feb 11, 2019 8:38 pm

This is the problem that many homes of that era and older have.
Back in the day that waxy paper was all that was used. It is literally impossible to get a good seal without removing the interior finish (drywall) and installing new proper vapour barrier but unless you are removing the rooms it’s really not worth the effort. Your layers of paint will do the major sealing in your home but the weak points are anything that punctures that surface . If you can seal around as many electrical boxes as possible that will go a long way to stopping drafts and leaks.
How thick is that old insulation in ceiling ? Likey just 3-1/2”? If so it will be R 10 likely at the most. Having some blown in insulation add on top of the other types would be your best option IMO.
What is generally done to add insulation value to exterior walls is to add rigid foam on the exterior over the plywood and then re finish the exterior.
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