Backer Rod is a foam material used to fill large checks and gaps between logs. It also provides support for chinking and sealants. Its primary purpose is act as a “bond-breaker” and promote two-point adhesion (see diagram), giving the joint and sealing material the ability to compress and expand as logs move. Sealants and chinking do not adhere to the backer rod - only to the log surfaces of the joint - allowing for movement without damaging the sealing material.

You should select backer rod based upon your particular needs. Open-cell type is recommended to speed drying. A closed-cell type is more moisture resistant. Please review FAQ's for more info.