Gas and Oil Home Heating Furnaces - Resolving insufficient insulation and improper attic vapor barrier.
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09-18-00, 12:09 PM
My 1000-s.f. attic has only 4 inches of unfaced fiberglass insulation. It is old and very brittle. A tar-and-paper vapor barrier, also brittle, was later added ABOVE the fiberglass, towards the attic space. There are no eaves or soffit vents, but about 800 s.i.'s of gable plus mushroom venting. I want to add insulation, but don't know whether I should:
(a) Do the easy thing: Assume that the 4" is not doing much insulating anyways and just lay new R-30 fiberglass with vapor barrier on top of it, so that the two barriers are touching,
(b) Do the hard thing: Remove all of the old 4" plus its barrier, and install new fiberglass with vapor barrier downwards this time, or
(c) Do a combination, i.e., do (a) over the high-moisture areas like kitchen and bath, and do (b) everywhere else.
Since there are no soffits, can I also install insulation into the corners where attic floor meets roof?
Incidently, I plan to install a small gable fan next spring and add more mushroom vents if needed.
(a) Do the easy thing: Assume that the 4" is not doing much insulating anyways and just lay new R-30 fiberglass with vapor barrier on top of it, so that the two barriers are touching,
(b) Do the hard thing: Remove all of the old 4" plus its barrier, and install new fiberglass with vapor barrier downwards this time, or
(c) Do a combination, i.e., do (a) over the high-moisture areas like kitchen and bath, and do (b) everywhere else.
Since there are no soffits, can I also install insulation into the corners where attic floor meets roof?
Incidently, I plan to install a small gable fan next spring and add more mushroom vents if needed.