Thermwell C22H Caulk Saver Backer Rod 0.5 in X 20 Ft

Product Description

The THERMWELL C22H is a polyurethane foam backer rod designed to reduce caulk consumption when sealing large gaps and joints. The rod is pressed into the gap before caulking, creating a backing surface so caulk is applied only where it performs — at the surface seal, not deep in the void. At 0.5 inches in diameter and 20 feet in length, the C22H is sized for common expansion joints, window perimeters, door frames, and similar applications found in residential and light commercial construction. It is made from durable, resilient, moisture-repellant poly foam that holds its shape under compression and accepts virtually any caulk or sealant type applied over it.

The C22H is suited for use in plumbing, HVAC rough-in, and general building envelope work wherever large gaps require sealing. It is commonly used around pipe penetrations, duct chases, window and door rough openings, and foundation transitions. Because it works with virtually every caulk and sealant type — silicone, latex, polyurethane, and butyl — it fits into existing workflows without requiring a dedicated sealant product. Installers press the rod into place by hand, then apply caulk directly on top.

Key Features

• Reduces total caulk volume needed by filling gap depth before sealant application
• Compatible with virtually all caulk and sealant types including silicone, latex, and polyurethane
• Made from durable, resilient, moisture-repellant poly foam
• Simple press-in installation — no adhesive or tools required
• 0.5 inch diameter fits standard expansion joints and framing gaps
• 20-foot length covers extended runs without splicing on most jobs

Compatibility

Designed for use as a backer rod with virtually any caulk or sealant type in residential and light commercial gap-sealing applications.

Installation Notes

No special tools are required — the rod is compressed and pressed into the gap by hand until flush or slightly recessed below the surface. Ensure the gap is clean and free of debris before inserting the backer rod. Apply caulk or sealant directly over the installed rod per the sealant manufacturer instructions. Do not stretch the rod along its length, as this reduces its effective diameter and may compromise the backing surface.