Insulation in new construction must be installed

• A. at the exterior wall joist headers (band joists)
• B. only between studs
• C. only in the attic ceiling
• D. around interior partitions

Answer: (A)

Insulation belongs where it protects the building’s exterior envelope, especially at places where heat can leak through the framing. The area around the exterior wall band joists (also called exterior wall joist headers) is a critical edge of the floor framing. It’s a common thermal bridge and can be easy to forget, since standard cavity insulation between studs doesn’t reach this rim area. By installing insulation around the exterior wall band joists, you close that path for heat transfer and help meet the required overall insulation value for the wall assembly. Insulating only between studs leaves the band joist region uninsulated, insulating only in the attic misses the wall edge, and insulating around interior partitions doesn’t address the exterior envelope.