DIYbanter - View Single Post - rock wool insulation in attic replace or add to it?

dpb

wrote:
....

Wow, so if I only have 2 inches of Rock Wool insulation in my attic I
only have a maximum of R value of R-8?

Sounds about right...2" of much of anything other than the new foams
isn't much actual insulation value...

... What is the recommended R value for attics? Isn't it around 40?

Depends on where you're located--in really cold climates, yes; more
moderate 30 or so is probably about the point of diminishing returns.

Your local po-co undoubtedly has energy conservation services and can
provide recommendations and quite possibly even do energy assessments at
no or very low cost...

--