Attic insulation….fiberglass or foam?
Dear GreenBuilding Advisor
I live in the suburb of Philadelphia and I am having one hell of a time trying to find the best way to insulate my attic. Here’s my short story, I am wondering if you could provide some guidance.
I am very interested in going green with my attic and upgrading my currently degrading fiberglass insulation. The catch…and its seems a debate of who you ask.
#1) The govt suggests (as does most building codes in the area) we get a total R value of R-38 (that’s about 12″ of compact fiberglass) or 5″ of closed cell foam (at R-7/inch) or 10″ of open cell foam (at R=3.8/inch).
#2) I have had 2 independent contractors to my house, and a 3rd a verbal quote over the phone about options. ALL of them say to use less insulation with spray, resulting in less cost for product but more importantly less R value. Each say about 5-6″ of open cell is what I would need for insulating the flooring of my attic (and removing the existing fiberglass) Overall this is a less R value = R19 or R21. The reason for my email.
Who do I believe? Do I really want to put all of this money into my attic for a sub R value ( R stands for resistance of heat flow?). Why would I do that? Any why would they try to push this one me? I have asked to see data – but the few things I have seen show “efficiency” or in conditioned attics where they spray the underside of the roof.
I understand that foam will block out every area where air flow is an issue, but my bigger issue is why would I choose a lower insulating product?
Who is right? Seems both sides have some issues to settle.
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