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July 22, 2014

A backer rod is a cylindrical type of foam used to fill cracks and gaps between building materials. It is used in a wide range of applications including tiling, flooring, window paneling and stoneware among others. In all these applications, it is used for three major purposes. These are; to control depth of sealant, to provide backing for the sealant to be applied, and to prevent triple bonding. When it comes to controlling the depth of sealant, the rod is used to ensure that the depth to be filled the sealant is half the width of gap to be filled. The rods have bond breaking properties hence do not bond with the sealant. They ensure that the sealant only bonds with the building material hence preventing triple bonding.

Installation of the backer rod is quite simple. The gap to be filled is cleaned thoroughly and left to dry. All contaminants that may alter the working of the sealant are removed. Once the gap is cleaned, the builder chooses an appropriate size and type of rod to use. In case insulation properties are required, one should use closed cell rods. Same case applies when the builder needs to produce an airtight seal. Open cell rods are used in all other indoor applications to fill different sizes of gaps.

The choice of backer rod diameter to use depends on the width of crack to be filled. The diameter should be slightly larger than the width of gap to be filled. For joints that are smaller than 19mm, the rod should be 3mm larger than the width of gap. Bigger joints will require a larger allowance than 3mm. however, these specifications are only appropriate for closed cell rods. When using open cell rods, the diameter should be 25 percent larger than the width of gap to be filled. Filling of the rod into the crack should be done using soft tools or rollers in order to avoid puncturing.