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?