The rim joist—also called the band board—is the perimeter board that sits on top of your foundation and supports your floor joists. This critical junction between your foundation and living space is one of the most significant sources of air leakage in most homes.
In Tulsa homes, uninsulated rim joists allow cold air to infiltrate in winter and hot, humid air in summer. Spray foam insulation seals and insulates this area in a single application, dramatically improving comfort and energy efficiency.
Why Rim Joist Insulation Matters
Air Leakage
Major Source
of home energy loss
Two-in-One
Seal + Insulate
single application
ROI
High Value
cost-effective upgrade
Energy auditors consistently identify rim joists as one of the highest-impact areas for air sealing. Because the rim joist area includes numerous penetrations for pipes, wires, and HVAC ducts, it's nearly impossible to seal effectively with traditional insulation methods.
How Spray Foam Solves the Problem
Complete Air Sealing
Unlike fiberglass batts that only provide insulation, spray foam expands to fill every gap, crack, and penetration in the rim joist area. It creates a continuous air barrier that stops infiltration completely.
Moisture Control
Closed-cell spray foam acts as a vapor barrier, preventing condensation that can occur when warm, humid air contacts the cooler rim joist area—a common cause of wood rot and mold growth.
Thermal Performance
With R-6.5 to R-7 per inch, closed-cell spray foam provides excellent insulation value in the limited space available at the rim joist. Just 2-3 inches achieves R-13 to R-21.
Signs You Need Rim Joist Insulation
Cold Floors in Winter
Floors near exterior walls that feel cold indicate air infiltration at the rim joist.
Drafts Near Baseboards
Air leaking through the rim joist often shows up as drafts at floor level.
Visible Gaps in Basement/Crawl Space
If you can see daylight or feel air movement at the rim joist, sealing is needed.
Pest Entry Points
Mice and insects often enter homes through gaps at the rim joist area.
The Installation Process
- Inspection: We examine the entire rim joist perimeter for gaps, penetrations, and existing insulation
- Preparation: Remove any ineffective existing insulation and clean the area
- Application: Apply 2-3 inches of closed-cell spray foam to seal and insulate
- Verification: Confirm complete coverage with no gaps or voids
Most rim joist insulation projects can be completed in a single day with minimal disruption to your home.