Where is the membrane applied?
Airtight layer placed below the joists
MEMBRANE IN INSTALLED SUB-AND-TOP
Airtight layer installed in a zig-zag pattern
Airtight layer placed above the joists
See the Buildwise article on insulating attic floors (Buildwise magazine, September–October 2024).
The attic must be ventilated.
HEATED ROOM & ATTIC
Between a heated room & an unheated attic
HEATED ROOMS
Same living unit & heated same way
HUMID & DRY ROOMS
Between a humid room & a living space
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