Air sealing and insulating overhanging floors is important to the overall building energy performance and thermal comfort of the home. The exposed underside of the floor can be a significant source of heat loss, due to air leakage and lack of insulation. It can also create cold floors and walls. The exposed floor is similar to a floor over an uninsulated crawlspace, and it is expected the subfloor and flooring will act as the bulk of the air barrier and vapour retarder. Air sealing is required at all joints and penetrations, and services in the overhang also must be insulated.

This air sealing and insulating procedure is for exterior overhanging floors. A similar procedure should be used for floors over car ports or other exposed floors.