Got my crawl space dug out so I can move around. Want to insulate w/ R19
bats. Joists are 2x6 approx. 24 inches on center. What's the best way to
hold up the insulation? Can't staple the flanges since they need to face up
towards the heated surface. Can't use the "wire struts" since the 24" on
center is only approximate. (± 1/2 inch). Was considering cutting strips
of Mylar and stapling them to the studs under the insulation.
Any other thoughts????
No matter how you put them up, you need chicken wire with small openings
stapled over the insulation to keep small animals out as they love to nest
in accessible insulation. The paper flanges won't keep anything out. They
can make quite a mess.
With fiberglass R value drops proportionatly as it gets colder below
32f, at -20 it might be 20-35% less effective, Foam excells in keeping
R value stable, it also doesnt settle. R value can be double that of
fiberglass, it keeps out moisture from your home and cold or hot air
infiltration. It should be painted to keep from oxidising and covered
in small wire as rodents will burrow. R 7 foam may be 3 times as
effective per inch, than fiberglass at cold temps. But there are many
types of foam to pick.
The flange is stapled and at the bottom you keeping moisture from
entering, dont think everybody has beeen doing it wrong on millions of
houses for decades.
This is in a crawspace between the first floor and earth. I would love to
simply staple the flanges BUT have been told the 'paper' always goes up
toward the conditioned (heated living space) side of the space. What gives?
Can I install it "paper down"?
In the attic heat rises so does moisture, in a damp crawl moisture and
cold incomming air rises to your inside. Ive seen quite alot of crawl
spaces and open buildings where it was done this way with no issues,
and mine maybe 80 years ago, but crawl spaces were dry, its the only
easy logical way to do it, and the paper down keeps air from going up
through easily. Read about how fiberglass looses efectivness at very
cold temps, paper down could help that issue. The Attic issue is to
keep attic wood dry so you dont mold then rot your roof away in a few
years with tight attics. Celulose and unfaced insulation without vapor
barrier are used all the time in attics. Staple it and be done, but
foam is really best if you have the $
Polystyrene or similar pushed in as a tight fit will do the job.
You need at least five inches thick to do a proper job.You must ensure
that you leave no holes, as heat always moves to cold and your heat
will move out through those holes.
Then the problem is that the floor and joists are poor insulators in
comparison to polystyrene and your heat will leak out through the wood
joists. The best solution the that is insulate above the floor.
Wood had a fairly high r value it is not a poor insulator. Insulate
above the floor, that idea is a laugh. His heat wont "leak out" the
joists, even less so than fiberglass batts. Go look at log home R
values. He has about 6.5" of wood.
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