I live in Elmore County Alabama (DOE Climate Zone 3A) and I had some major refurbishments done, in order to improve my home.
First, I had my attic spray foam insulated (i.e. retrofit from vented to unvented attic) with closed-cell foam. The contractor has approx 8 years exp w spray foam, and 20+ years as an insulation contractor. I opted for the closed-cell foam, as recent code recommends impermeable barrier to the roof deck. We left the fiberglass blown in insulation in-place over the ceiling joists, and contractor stated that was O.K. (i.e. cause no harm … can be removed later).
Second, I replace the 3-1/2 ton air-source heat pump with a 2-ton ground source heat pump. The HVAC contractor did the Manual J and with the ducts in the attic, the spray foam attic retrofit enabled me to go w a smaller GSHP unit.
With that in mind, the attic is a lot cooler than unvented (i.e. 105F versus 140F on a 95F day), but not 10-15F different from house temp.
Took some temp/humidity readings today (20 Jul 11), they are Outside temp: 80F, Humidity: 84%; Indoor house temp: 78F, Humidity: 70%; Attic temp: 86F, Humidity: 63%.
My questions are:
Should I remove the fiberglass blown in insulation from the ceiling joist? Is there any benefit?
If I remove the fiberglass blown in insulation, should I use some of it to fill the remaining 2x6 roof deck space (i.e. spray foam filled 2 1/2", leaving 3"). I would use rigid foam board affixed to the bottom of roof decking 2x6, then fill from top.
Are the indoor house and attic humidity readings reasonable for my area(CZ: 3A), at this time of year (Jul)?
Thanks for your assistance.