What is backer rod?

Backer rod is a flexible rod or tube made of closed-cell polyethylene foam used in construction and waterproofing applications. It is inserted into joints and gaps between building materials to provide a backstop for sealants and caulking, preventing the sealant from sinking too far into the gap.

Backer rod comes in various sizes and shapes to fit different joint sizes and configurations, and is available in different compressibility levels to accommodate different movement requirements. It is easy to compress and insert into joints, and can be trimmed to fit the desired length.

Using backer rod in conjunction with sealants helps improve the effectiveness and longevity of the sealant, as it allows for proper sealant depth and prevents three-sided adhesion, which can compromise the seal. Additionally, backer rod helps reduce the amount of sealant needed, saving time and money on the overall construction project.

Overall, backer rod is a versatile and essential component in construction and waterproofing projects, helping to create durable and long-lasting seals in various applications.