Joseph Meehan wrote:
Jason wrote:

Is there such a thing as too much attic insulation? I have R38 in
the attic at the moment, but the local building inspector says they
like to see at least R50 in new homes. Would adding another layer of
R38 (total R value would then be R76) perpendicular to the existing
layer of fiberglass be overkill? Or will it make a difference? Does
attic insulation really cut down on heat gain in the summer and heat
loss in the winter? Or is there some other place to look to cut down
on heat gain?
Thanks,


The more the better. As noted you should not add a vapor barrier.
After so much additional there are diminishing returns, but it would appear
for the comments of the building inspector that you live in an area where
the extra would be a good idea.

I don't know exactly what I have, but I know I doubled what the builder
put in 12 years ago.


Read an article today on blown in foam insulation. 90% of benefit is
covered in the basic application (i.e. r38 for attics), adding 50% more
gets an extra 5% of benefit, adding another 50% more gets an extra 2.5%
of benefit.....

Plus there are articles a plenty that describe what happen INSIDE
fiberglass insulation in cold climates. R76 drops to R25!!!!