M-d Building Products 71480 Backer Rod 1/2 in X 20 Ft Gray

Product Description

The M-D BUILDING PRODUCTS 71480 is a closed-cell polyethylene backer rod designed for use before caulking in gaps and openings larger than 1/2 inch wide by 1/2 inch deep. The nonabsorbent, closed-cell construction prevents moisture intrusion into the foam itself, keeping the backing material stable over time. Its primary function is to control caulk depth and prevent three-point bonding, which can cause premature caulk failure at joints and seams. Installers in construction, weatherization, and building envelope work rely on this type of pre-caulking material to produce durable, properly dimensioned caulk joints on both interior and exterior applications.

This backer rod is suited for residential and light commercial projects where gaps or control joints exceed 1/2 inch in both width and depth. Common applications include expansion joints, window and door frames, concrete control joints, and masonry openings where a proper caulk backing is needed to achieve a two-sided bond. The 20-foot roll length makes it practical for single-joint runs or multiple smaller fills on a job site without excessive material handling.

Key Features

• Closed-cell polyethylene construction resists moisture absorption
• Prevents three-point bonding for longer-lasting caulk joint performance
• 1/2 inch diameter fits gaps and openings larger than 1/2 inch x 1/2 inch
• 20-foot roll provides continuous length for single or multiple joint fills
• Nonabsorbent material maintains shape and density after installation

Compatibility

Designed as a pre-caulking backer for use with standard caulks and sealants in gaps and openings larger than 1/2 inch wide by 1/2 inch deep on residential and commercial building envelope joints.

Installation Notes

Backer rod is typically installed by construction trades, weatherization contractors, or skilled DIYers working on building envelope sealing. Press the rod firmly into the joint so it seats at the correct depth, leaving adequate space for the caulk bead above it. Do not stretch or compress the rod excessively, as this can alter the diameter and affect caulk depth control. Ensure the joint is clean and dry before installation to promote proper sealant adhesion.

Technical Specifications

• Material: Closed-cell polyethylene
• Diameter: 1/2 inch
• Length: 20 feet
• Color: Gray
• Weight: 0.132 pounds
• Cell Type: Closed-cell, nonabsorbent

Standard Information

• Brand: M-D BUILDING PRODUCTS
• Manufacturer Part Number: 71480