Do it Yourself: Re: [DIY] Closed Cell foam insulation

25 January 2013

Re: [DIY] Closed Cell foam insulation

Inland, Northern California.
Regards,
S.

--- In DoIt_Yourself@yahoogroups.com, freespirt2050 gdb7edc wrote:
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> If your in a dry climate like Phoenix it makes sense, wet climate like Houston, not a good idea. Not knowing your climate, those two examples of where you could use the foam may be helpful. Trapping moisture in a wet climate like Houston would not be good for the house.
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> ________________________________
> From: Strat
> To: DoIt_Yourself@yahoogroups.com
> Sent: Tuesday, January 22, 2013 7:06 PM
> Subject: [DIY] Closed Cell foam insulation
>
> Â
> Recently I read a debate in fine home buildiig mag on benefits of retrofitting an old homes exterior with 2-inch closed cell "rigid sheets", y'all can look it up if you're interested in reading it. But the long and short of it is:
> My old home which probably has no kind of insulation in the walls and that makes the house hard to heat during winter.
> Having researched options, I see basically 4 possible approach to insulating the walls:
> 1-spray closed cell foam between the studs and button up with new siding.
> 2-spray open cell foam, which costs less but doesn't have vapor barrier properties of closed cell.
> 3-fill the cavities with damp cellulose
> 4-cover over the studs with 2" sheets of rigid foam sheathing, tape the seams, cover with a wrap, then apply the siding.
>
> Its this last approach that's got me fired up.
> I don't understand why you would build up the exterior thickness over the studs by 2 and 5/8, that's crazy.
> Not only does this pose new problems for re-flashing all the doors & windows, but also I wonder how the heck is the exterior siding going to attach to the studs with 2 and 5/8 space between them!?
> It seems 4 inch galvanized screws would be the only option, heck you can't secure the siding to foam!!
>
> My preference is to shoot closed cell foam in the wall cavity every 16 inch. This ensures all the walls, electrical outlets, sills and ceiling transitions are sealed tight with a vapor/moisture barrier which offers better R value per inch than the other options.
> You can then wrap that with Tyvek and nail in James Hardi boards with a nail gun, bang bang bang, you're done.
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> No need to spend a lot of extra money on foam fastners, and 4 inch galvanized screws for securing siding to the studs. Best of all, I preserve the original thickness over the studs and minimize the need for custom flashing around windows.
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> There is yet another evil which is sizemic movement here in California the ground moves! These foam sheets are not speced to be sheer walls and I would not bet that in a year or two the tape that seals all those seams is going to hold "air-tight", in fact I bet it won't.
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> In closing I'm no expert, just a home owner, but I honestly don't see the logic in wrapping the house with rigid foam sheets.
>