CRL 3/4" Closed-Cell Foam Backer Rod 100 ft for Caulking

• Easy Control of Sealant Application Thickness
• Non-Bonding Surface – No Additional Bond Breaker Required
• Compatible with All Cold-Applied Sealants

CRL Closed Cell Backer Rod (SKU: EF34C) is a round, flexible polyethylene foam with an exterior "skin" that controls sealant depth and promotes proper joint design. This closed-cell backer rod acts as a reliable backing material for elastomeric and other cold-applied sealants, preventing excessive sealant use and enabling the preferred "hourglass" bead shape in expansion and control joints. Its non-bonding surface prevents adhesion to joint walls, allowing sealants to flex and reducing stress at bond points.

CRL Closed Cell Backer Rod is available in diameters from 1/4" to 2" (7 to 50 mm).

Closed-cell construction resists water absorption and will not wick moisture to joint walls, preserving adhesive performance. Ideal as a polyethylene foam backer rod for curtain walls, precast panels, parking decks, door and window frames, coping, floor and deck joints, and building rehab projects.

Temperature Limits:
-45°F to 160°F (-43°C to 71°C)

Application:
Commonly used in expansion/control joints with cold-applied sealants; compatible with a wide range of sealant chemistries (not for hot-applied sealants or hot melt adhesives above 160°F / 71°C).

Size Selection:
Choose a backer rod approximately 25–50% larger than the joint width to ensure a tight fit and proper sealant depth; correct sizing controls bead depth and prevents back-side adhesion.

Storage:
Store in a well-ventilated area out of direct sunlight. Keep away from heat sources and open flames.

Joint Preparation:

• New Joints: Remove form-release agents, curing compounds, and debris. Ensure joint is clean and dry before applying sealant.
• Repairing Old Joints: Remove old sealant or filler; use wire brushing and air blasting. If using compressed air, use moisture and oil traps.

Installation Instructions:

1. Prepare the joint per the Joint Preparation steps.
2. Measure and Select: Pick the correct backer rod diameter for the joint width.
3. Set Depth: Install to the depth recommended by the sealant manufacturer so the sealant forms an "hourglass" profile.
4. Use the Right Tools: Install with a blunt tool or