Rigid foam vs spray foam in attic conversion
My 1964 house in North Carolina’s zone 4 has its upstairs HVAC in the attic. The attic is flanked by brick chimneys and gable vents on both sides. There is a ridge vent as well, but no soffit vents. The soffits are not very deep.
I’ve been in the house about 11 months and have an excuse to replace the gas furnace and AC in the attic. Based on the info on this website, I should convert the attic to an unvented space using closed cell spray foam and install a high efficiency gas furnace and AC. I’m concerned about a couple things with this approach:
1) not being able to detect a roof leak under spray foam, and
2) off-gassing of the spray foam and harm to the home’s occupants (children).
Is the solution to install rigid foam under the rafters to create an air and thermal barrier between the attic and the roof? Does anyone have experience with such a “super” attic insulation system?
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