Stop Drafts & Lower Energy Costs

Rim joists (also called band joists) represent one of the largest sources of unsealed air infiltration in residential and commercial buildings. Located where the concrete foundation meets the wood floor framing, uninsulated rim joists allow cold winter drafts, humid summer air, dust, and pests to freely penetrate your basement and crawl space. Spraying low-pressure closed-cell polyurethane foam across the perimeter rim joist creates a continuous thermal envelope and permanent air seal that stabilizes indoor temperatures, reduces HVAC workload, and improves overall energy efficiency.

Why Spray Foam Is Essential for Rim & Band Joists

• Complete Air & Vapor Sealing: Unlike traditional fiberglass batts—which allow air to pass through and trap moisture against wood plates—closed-cell spray foam expands rapidly to seal every gap, rim joist pocket, wire penetration, and sill plate seam.

• Moisture & Mold Prevention: Warm interior air contacting a cold basement rim joist causes condensation, leading to timber rot and mold growth. Closed-cell foam acts as a class-II vapor retarder, eliminating thermal bridging and condensation points.

• Eliminates Cold Floors: Sealing drafty rim joists stops cold air from washing under first-floor subflooring, keeping hardwood and tile floors noticeably warmer during winter months.

• Pest & Draft Barrier: Creates an impenetrable structural barrier that deters rodents, insects, dust, and outdoor allergens from entering through foundation sill plate gaps.