Backer Rods : Polyethylene Backer Rod

Backer rod provides filler material for gaps between building materials, such as concrete, tile, or window paneling. The rods allow you to control the depth of joint sealant, by filling the space with foam or plastic. Using them prevents triple-bonding, which is when sealant bonds with both sides of the joint and the underlying material. This can cause the sealant to be pulled in three ways, increasing the chance of cracking.

Metro Sealants carries two brands of backer rods – Denver Foam and Armacell ITP. Denver Foam is made of an open cell polyurethane plastic and is an excellent backer for elastomeric and other applied caulking sealants. It is primarily used for indoor applications. It comes in sizes ranging from 5/8” to 2”. Select a rod slightly larger than the gap you are trying to fill.

Armacell ITP is made of closed cell polyethylene foam and is soft, pliable, and non-gassing. It is best used on outdoor applications or when water resistance is needed. It comes in sizes from 3/8” to 4”.

To install either type of backer rod:

  1. Clean the surface prior to installation, removing all old caulking or any dirt or dust.
  2. Once everything is dry, push the backer rod into the gap so it is below the surface of the material.
  3. Starting on one side of the joint, run a bead of caulk or sealant along the gap where the backer rod meets the material.
  4. Run another bead adjacent to and touching the first one. Continue to run beads until the gap is covered and you reach the other side of the backer rod.
  5. Run a bead of caulk or sealant on the material adjacent to the joint, completely sealing the joint.
  6. Use a spoon back or putty knife to shape the joint.
  7. Allow the sealant to dry before applying a surface finish, if desired.
  8. If you have questions about selecting this or other materials for your project, contact us and one of our friendly staff will help you.

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