Air Sealing the Lid

Inadequate sealing at the top and bottom of the wall continues to be a major source of building leakage in many new homes. The code doesn’t specify how to air-seal the top plates, allowing builders to innovate. Here are some techniques that work.

Walls to Ceiling

In this detail, Indigo Ruth-Davis pulls taped housewrap across the top plate to connect the exterior air barrier on walls with the ceiling drywall, which functions as the air barrier across the lid. (For more about this specific technique, see "Air Sealing Techniques from a Passive House Pro.")

Air Sealing the Lid

Architect, Steve Baczek and builder Jake Bruton devised a similar detail using peel-and-stick ...

Air Sealing the Lid

... pulling it across the top plates ...

Air Sealing the Lid

The inside edge of the peel-and-stick will be picked up by the ceiling drywall, which serves as the air barrier on the lid. (For more on this detail, see "Air Sealing That Works.")

Air Sealing the Lid

A variation on the theme: Here, 7/16-inch Zip System is used as a portico ceiling outside, and is extended across the top wall plates. Inside, the Zip System aligns with the ceiling drywall (to come). Also note the Zip System sheathing, which separates, and seals, a second-floor living area from the open, vented attic in the foreground - a critical detail to ensure a continuous air barrier.

Air Sealing the Lid

In this home by Aarow Building, the ceiling serves as the air barrier at the lid. Partition walls are framed after the ceiling drywall has been hung. Note that while the cracks in the drywall at the top-plate line do not create air leaks (a drastic reduction in air leakage), the hole for wiring and other mechanical penetrations will still need to be air-sealed.

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