Thermwell C22CP Caulk Saver Backer Rod 0.5 in X 250 Ft

Product Description

The THERMWELL C22CP is a closed-cell foam backer rod designed to fill medium-width gaps prior to caulking. Measuring 0.5 inches in diameter and 250 feet in length per roll, this contractor pack provides enough material to cover large-scale joint and seam applications without frequent reordering. The foam is moisture repellent, which helps prevent water infiltration at the backer layer. By pre-filling gaps with backer rod before applying sealant, installers reduce the volume of caulk required and achieve a more consistent, tooled joint. This product is used by plumbers, HVAC technicians, and general contractors when sealing penetrations, expansion joints, and building envelope gaps.

The C22CP is suited for residential and light commercial applications where medium-sized gaps need to be backed before sealant is applied. Typical uses include sealing around window and door frames, control joints in concrete or masonry, pipe penetrations through walls, and HVAC duct penetrations. The contractor pack includes 4 units, each containing 250 feet of backer rod in a dispenser box for controlled, tangle-free payout on the job site.

Key Features

• 0.5-inch diameter fits medium-width gaps and joints
• 250 feet per roll provides extended coverage on large projects
• Moisture-repellent foam construction resists water at the backer layer
• Dispenser box allows controlled payout and reduces material waste
• Contractor pack of 4 rolls reduces per-unit cost on high-volume jobs
• Reduces caulk consumption by pre-filling gap depth before sealant application

Compatibility

Designed as a general-purpose backer rod for use with most paintable and non-paintable caulks and sealants in residential and light commercial construction and mechanical applications.

Installation Notes

Backer rod is typically installed by pressing the foam into the gap using a blunt tool until it sits at the correct depth, leaving sufficient space for the sealant layer above. Ensure the gap is clean and dry before installation. Do not stretch the backer rod during installation, as this reduces its effective diameter and can compromise the sealant joint. Follow sealant manufacturer guidelines for proper backer rod depth-to-width ratios.