The Construction Gap Filler (Backer Rod) is a precision-manufactured, compressible foam material designed for joint control, sealant optimization, and long-term joint performance in construction assemblies. It is used primarily as a bond breaker and depth control medium in expansion joints, control joints, and gaps prior to sealant application.

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Manufactured from closed-cell or open-cell polyethylene foam, the backer rod provides a uniform, non-absorptive backing that supports sealants while preventing three-sided adhesion—an essential requirement for proper sealant movement and durability.