Module 16 - Rim and band Joists.pptx

STRAND Energy-Star Training Rim and band Joist © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage To provide an air barrier between the garage and the adjoining conditioned space, solid blocking is often used to air seal joist bay openings spanning over the garage and condit...

STRAND Energy-Star Training Rim and band Joist © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage To provide an air barrier between the garage and the adjoining conditioned space, solid blocking is often used to air seal joist bay openings spanning over the garage and conditioned space. A rigid material like rigid foam board, drywall, OSB, or plywood can be cut to fit each joist bay opening. Each piece must be cut to fit then nailed and caulked or spray foamed into place, which is a labor-intensive process. © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage Air seal the rim joist of the wall shared by the garage and the house. Design walls adjoining garages so that the rim joist board runs parallel to the common wall, providing a continuous natural air barrier. Where ceiling joists run perpendicular to the adjoining wall one option is to install a continuous rim joist to separate the two areas with separate but aligned ceiling joists on each side of the rim joist © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage Another option is to install solid blocking material in the joist bays over the common wall. Cut rectangles of rigid blocking material (plywood, polyisocyanurate, extruded polystyrene, etc.) to fit each floor joist bay cavity. Install a backstop for the blocking material by tacking furring strips to the joists in line with the foundation or house wall. Insert rigid pieces into each joist bay and fasten with caulk or nails .When using I-joists, make sure to cut the blocking to fill the irregular shape of the opening .Also seal holes in open-web floor trusses at the shared wall, if needed Use caulk or spray foam to air seal all four edges in each bay. Make sure to completely air seal around the rigid air barrier to prevent moist air from reaching and condensing on the rim joist. © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage Insulate the rim joist with additional rigid foam that is caulked or foamed into place or with spray foam. Use urethane spray foam insulation to cover the rim joist, and seams with the top plate below and subfloor above Medium-density (closed-cell, 2 pounds/cubic foot) or low-density (open-cell, 0.5 pounds/cubic foot) foams provide acceptable results. Open-cell foams might require additional vapor and condensation control measures in IECC Climate Zone 6 and higher. Foam can be applied by a spray foam subcontractor or use two-part spray foam kits. © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage Spray foam in band joists is typically concealed between floors so no other thermal barrier is required; however, the International Residential Code (IRC) allows the spray foam at rim joists to be exposed in basement and crawlspace applications (i.e., without a 15-minute thermal barrier such as drywall) as long as the thickness is less than 3.25 inches and has a density range of 0.5 to 2.0 pounds per cubic foot (see 2009 IRC R316.5.11). Closed-cell, 2-PCF spray foams were approved in the 2003 IRC and open-cell 0.5-PCF foams were approved in the 2009 IRC, along with any intermediate densities (BSC 2009). © 2023 STRAND Dallas I Texas 972 620 8204 Air Sealing Attached Garage © 2023 STRAND Dallas I Texas 972 620 8204