For more on air-sealing solutions, visit the JLC Field Guide.
Air-Sealing Knee Walls
Knee walls are an area of the home where airsealing is often incomplete. The walls and roof might get done, but frequently the floor is left wide open. The best way to handle a knee wall area is to move the thermal barrier to the roofline (left) and stand up the knee walls after the ceiling has been drywalled. For production builders who may have less control in scheduling trade partners, the knee wall can serve as the thermal barrier (right), as long as sheathing is installed on the back side. Also, note the blocking between floor joists. Without this critical framing addition, ventilation air from roof vents can flow freely though the floor cavity.