Backer Rod Foam Insulation

Backer Rod can be used in various construction projects, but builders normally choose it for filling gaps or joints where materials come together. The foam is used to fill most of the void which is then coated with sealant (mortar, caulk, etc.) to create a watertight, airtight seal. It controls the sealant depth, insulates the underside of the sealant, and allows proper tooling and wetting of joint surfaces. Using it in construction projects speeds up curing times and allows the building materials to flex, move and bend in response to environmental factors like heat, cold, wind, humidity or UV light.

Backer Rod Diagram

Common Applications:

• Glazing Operations
• Window and Door Applications
• Expansion Joints
• Log Construction
• Partitions
• Pavement Joints
• Repairs


Backer Rod comes in diameters typically ranging from ¼” – 4″ and is a non-absorbent, closed-cell, compressible material. It is chemically inert and will resist gasoline, oil and most other solvents.