M-d Building Products 71464 Gray Backer Rod 3/8 in X 20 Ft

Product Description

The M-D Building Products 71464 is a closed-cell polyethylene backer rod designed to fill gaps and openings before caulking. Measuring 0.375 inches in diameter and 20 feet in length, it is used as a pre-caulking filler to control joint depth and prevent three-point bonding, which can compromise sealant performance. The nonabsorbent, closed-cell construction resists moisture absorption, keeping the backer rod stable and effective within the joint. This product is installed by general contractors, sealant applicators, plumbers, and other trades during sealing and waterproofing work on both interior and exterior applications.

This backer rod is suited for joints and gaps larger than 0.5 inches x 0.5 inches where a backing material is needed to support and shape a caulk or sealant bead. Common applications include expansion joints in concrete, masonry, door and window perimeters, and other construction assemblies where proper sealant profile and depth-to-width ratios are required. The 20-foot length provides adequate coverage for typical residential and light commercial sealing tasks.

Key Features

• Closed-cell polyethylene construction is nonabsorbent and moisture-resistant
• Prevents three-point bonding for improved sealant flexibility and longevity
• Use in gaps larger than 0.5 inches x 0.5 inches as a pre-caulking filler
• 0.375-inch diameter fits standard joint widths in construction and sealing applications
• 20-foot roll provides continuous length for efficient installation

Compatibility

Designed as a pre-caulking backer material for use with standard caulks and sealants in joints and gaps exceeding 0.5 inches x 0.5 inches in residential and light commercial construction assemblies.

Installation Notes

Install the backer rod into the joint recess before applying any caulk or sealant. The rod should be seated firmly so the sealant contacts only the two opposing joint faces, not the backer rod face, to prevent three-point bonding. No adhesives or specialized tools are required for placement; a blunt roller or dowel is commonly used to press the rod to the correct depth. Follow sealant manufacturer guidelines for minimum joint depth-to-width ratios after backer rod installation.

Technical Specifications

• Material: Closed-Cell Polyethylene
• Diameter: 0.375 inches
• Length: 20 feet
• Color: Gray
• Weight: 0.096 pounds
• Unit of Measure: Each

Standard Information

• Brand: M-D Building Products
• Manufacturer Part Number: 71464