Designs That Work
Air Sealing / Air Drywall Approach Details
A tight building enclosure is necessary to control the movement of air
in and out of building assemblies. This is important for energy
conservation, thermal comfort and building durability. Moisture laden air
moving into wall or roof assemblies (particularly from the exterior during
cooling in hot-humid climates or from the interior during heating in cold
climates) may lead to condensation and result in deterioration of moisture
sensitive materials. An air flow retarder can be installed on the interior
or the exterior side of the envelope or on both sides. For more detailed
discussion on air flow retarders, click
here.
Controlling air movement through the building enclosure requires sealing
both the "big" holes and the "little" holes. The big
holes occur behind bath tubs and showers on exterior walls, behind
fireplaces, and where soffits or utility walls (double wall with chase)
meet exterior walls or ceilings. Recessed lights collectively can be a
really big hole in the ceiling assembly. These big holes are responsible
for wasted energy (high utility bills), frozen pipes and condensation that
can cause mold and wood decay. These big holes are easy to seal during the
framing stage but only when someone has the responsibility for making sure
it gets done.
The small holes occur between framing members (such as band joist to
sill plate), around electrical boxes and where plumbing or wiring
penetrate the envelope. The Air Drywall Approach uses the gypsum board to
provide an interior air flow retarder. The gypsum board is sealed to the
framing members at the perimeter of exterior walls and around penetrations
such as doors, windows, and attic hatches. The gypsum board is also sealed
to electrical boxes on exterior walls. Air cannot move through the gypsum
board and the taped corners. Details of air sealing and the ADA are
illustrated below. Photographs of many of these details are also shown in
the file of photos attached to each
Designs that
Work climate design.
Air Sealing Details
Click on detail for expanded view.
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