Best insulation and sealing for a tucked-under-garage ceiling?
We are purchasing a circa 1966 Cape in the Philadelphia are with the garage tucked under the master and guest bedrooms and two baths. The garage ceiling is currently covered with Homasote, but there are small areas where we can see an underlying plaster ceiling with missing chunks. The joists are 2x10s and there appears to be some fiberglass insulation batts in place.The HVAC ducts run below the joists and are mostly covered in Homasote, but several feet of ducts near the overhead door opening are exposed and uninsulated, but with remnants of asbestos.
We suspect that the rooms over the garage have been uncomfortably cold in winter and hot in summer, and know that the current owners utility bills are very high. We are also concerned about the safety hazards of the asbestos plus the currently damaged fire-break and carbon monoxide risks.
Since we plan to use the first floor master bedroom, our first project will be to tear out the garage ceiling, remediate the asbestos, seal and insulate the HVAC ducts, then re-insualate the ceiling joists and cover with 5/8″ drywall. We thought that blown-in foam would give us the best insulation plus a good air and carbon monoxide barrier, but a contractor we consulted thought that new fiberglass batts followed by plastic film and the drywall would be adequate and far cheaper. What do you think? Since the garage ceiling will also need re-wiring for lights and door openers, would you run the new electrical wiring under or over the drywall?
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