Conduction of heat through the walls of a home accounts for about 10% of the heat gain for the entire building (LBNL 1999). Infiltration through walls causes additional heat gain. This heat gain can be reduced by using “cool” white or reflective wall cladding and finishing materials as described in the guide "Cool Roofs and Walls", by providing shading as described in the guide "Landscaping to Reduce Cooling Load", and by air sealing and insulating the walls. There are several guides in the Building America Solution Center that describe effective ways to air seal and insulate new and existing homes.
Wall Air Sealing
Guides for air sealing walls in new homes include the following guides:
- Continuous Air Barrier in Exterior Walls
- Air Sealing Drywall to Top Plate
- Air Sealing Sill Plates
- Air Sealing Window and Door Rough Openings
- Air Sealing Structural Insulated Panel (SIP) Seams
Guides for air sealing walls in existing homes as a retrofit measure include the following:
- Flashing of Wall Penetrations in Existing Homes
- Air Seal Top Plates or Blocking Missing at Top of Walls Adjoining Unconditioned Spaces
- Roof/Attic to Exterior Wall Air Control Upgrade
Wall Insulation
Guides for insulating walls in new homes include the following:
- 2009-2021 IECC and IRC Minimum Insulation Requirements for New Homes
- Continuous Rigid Insulation Sheathing
- Taped Insulating Sheathing Drainage Planes
- Insulation Installation Achieves RESNET Grade 1
- Structural Insulated Panels (SIPs)
- Insulated Concrete Forms (ICFs)
- Double-Stud Wall Framing
- Double Walls
- High-Thermal-Mass Construction
- Advanced Framing: Insulated Interior/Exterior Wall Intersections
- Advanced Framing: Insulated Headers
- Advanced Framing: Insulated Corners
- Advanced Framing: Minimum Wall Studs
- Stucco Over Rigid Foam Insulation
- 2015 IECC Code Level Insulation – DOE Zero Energy Ready Home Requirements
Guides for insulating walls in existing homes as a retrofit measure include the following:
- Batt Insulation for Existing Exterior Walls
- Blown Insulation for Cavities of Existing Exterior Walls
- Rigid Foam Insulation for Existing Exterior Walls
- Spray Foam Insulation for Cavities of Existing Exterior Walls
- Spray Foam Insulation Applied over the Siding of Existing Exterior Walls
- Seismic and Insulation Retrofits of Solid Masonry Walls
- Vinyl Siding with Integrated Rigid Foam for Existing Walls
- Rigid Foam Board Insulation for Existing Band Joists
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The following authors and organizations contributed to the content in this Guide.