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Critsmcgee

join:2011-12-02
Reviews:
·Verizon FiOS
reply to lazidazi

Re: Insulating Attic

said by lazidazi :

Okay, now - please don't anyone get fussy with me for asking an ignorant question.

RE Xcal's pictures, insulating attic with rigid foam board on the bottom edge of roof rafters: When one does this, is insulation at/between the ceiling joists then not needed? Is the rigid insulation at the rafters all that's needed for the attic? [including, of course, what he's done on the gable ends, et al]

You use fiberglass insulation under the rigid board to create a higher r-value insulation while moving the thermal envelope. R-19 fiberglass is the most common under the rigid board which is R-13 for a 2" thickness for a total of R-32. If you can get more then R-19 under the rigid board that's great. Some people use foam instead of fiberglass.


lazidazi

@frontiernet.net

You use fiberglass insulation under the rigid board to create a higher r-value insulation while moving the thermal envelope.

Appreciate your reply!

To be sure I understand, one would put (at least) R-19 fiberglass bats, between roof rafters, then put rigid board along bottom edge of rafters. Correct?

I currently have blown-in insulation between [8"] ceiling joists. If I attend the rafters, as per above, will that then suffice [assuming all other air gaps between living space & attic are stopped] as far as insulating the attic?

Attending the rafters w/insulation is going to be quite expensive!



AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1

said by lazidazi :

Attending the rafters w/insulation is going to be quite expensive!

check your ROI when looking at costs and finance accordingly.
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