While it isn't insulation, there is a product out there that will keep
your from roasting in the summer. Check out radiant barrier. It is
basically a roll of paper with scrim in it that has aluminum foil on one
or both sides. It reflects the heat back. You just staple it across the
bottom of your roof framing. IT is usually perforated so that moisture
won't build up. If you go with the single sided foil, install it with
the foil down. If you install it foil side up the efficiency of the foil
will decrease as dust accumulates on top of it. By putting the foil
down, the paper gets the dust and it doesn't affect the reflection of
heat as much. I use double sided barrier my self. Last time I bought
some was about 5 years ago, and a 4'x100' roll was about $100. You might
be able to find someone in your area that uses it that will sell or give
you some of their roll ends to do your garage.
As far as insulation goes, you might consider adding foam insulation to
the bottom of the framing, but hold the insulation back at the top and
bottom edges of the roof to allow for air circulation. Sure, it won't be
as efficient as completely covering the ceiling, but it will be better
than nothing. Also, check with some professional insulation companies,
and your local building inspection office.
Thusly spake Jim Franklin, On 12/15/2009 10:22 AM:
> The local lumberyard said even unfaced fiberglass would trap the
> condensed moisture and rot out the roof.
> I think rigid foam against the decking would also trap moisture
> migrating through the joists and into the decking.
> There isn't enough room to put in a false ceiling.
> It'd probably be cheaper for us to tear down & rebuild the garage than
> to have spray foam installed.
> Am I missing any options?
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Pat Horne, Owner, Horne Systems
(512) 797-7501 Voice 5026 FM 2001
Pat@HorneSystemsTx.com Lockhart, TX 78644-4443
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