I have 6" of rock wool in my attic. I'm in Portland, Oregon.
About half of my 1400 square foot ranch is closed off and unheated.
Much of the attic over the unheated space and part of the heated space
is floored and covered with boxes of junk.
For about $200, I can double the insulation in the attic over the
part that I actually live in. Sounds like a no-brainer.
BUT, I had an energy audit and they told me that If I didn't
insulate ALL of the attic, including ripping out the flooring and
moving all the boxes elsewhere, I'd get almost NO gain.
I'm haunted by he ghost of my thermodynamics professor
saying that "that's crap!"
When you insulate an area of ceiling, you get less heat loss through
that area and the rest stays unchanged...but you don't lose anything.
If I turn down the thermostat because the better-insulated rooms stay
the rest of the house gets cooler and I should have a net gain even
in the insulation-unimproved part of the house due to the lower
My objective is NOT to make the house warmer. It's to keep the part
I live in at the same temperature using less gas.
So, do I trust an experienced energy expert or the ghost of a
And I have the same question about insulating the floors
in the inhabited part only.