Question for HVAC gurus.
Alim Nassor wrote:
On Mar 6, 2:54 am, "Bob F" wrote:
Alim Nassor wrote:
On Mar 6, 12:40 am, "Bob F" wrote:
Alim Nassor wrote:
Hi guys. My wife and I are in the late planning stages of building
our new home. I want it to be as energy efficient as possible. We
are having a slight disagreement.
I want foam insualtion in walls and attic. She is ok with that.
What we disagree about is how to do the attic.
Her ex-husband is a HVAC contractor. He says we should use the "
foam the underside of the roof, seal the attic and semi condition
it" method. Our builder agrees.
My problem with that is, why would I want to semi condition an
area the same size as my house if I am never going to use it for
anything? I want to foam the attic floor, and make sure the attic
is well venitaled. Why is allowing my warm and cold air (that I am
paying to heat and cool) to migrate up into my attic a good idea?
Isn't it more efficient to keep that expensive air in the house by
well insulating the attic floor?
Can anyone give me advice on why my thoughts are wrong?
You need good ventilation under the roof deck to cool the roof.
Otherwise, the
shingles will die early.
Insulating the roof will require more insulation for the same job.
Why foam? You can probably use fiberglass for way less $, and it
can be removed
if you need to work on the wireing. In an unused attic, you can
have as much
insulation as you want.
Will you really have an attic space, or just a bunch of gaps
between trusses?- Hide quoted text -
- Show quoted text -
The roof will be galvanized R-panels. The roof framing will be
trusses. Foam is a good air barrier as well as insulation.
A layer of plastic will be just as good of an air barrier.
How does the foam survive over time when subjected to the extreme
heat a metal roof will transfer? Especially if there is not a
ventilated airspace between them.- Hide quoted text -
- Show quoted text -
I don't know. Another reason to insulate the floor and not the roof?
That's my thought.
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