Backer rods are cylindrical pieces of foam that are used to limit the amount of sealant or chinking in joints or cracks. Many varieties are available to suit the size of the joint being sealed. In addition to shape, the cell structure of the foam is also important. This includes closed cell, open cell, and bi-cellular structures, depending on the joint application, flexibility desired, and sealant used. Backer rod material is typically made of polyethylene or polyurethane foam, which makes it compatible with common joint sealants and caulking.
In order to keep a log structure weather tight, both caulking and chinking material need to be properly applied. Using backer rod and chinking can significantly reduce heat loss from the log walls, as well as from windows and doorways. This can result in significant savings on energy bills and future repairs. Before chinking a log cabin home, installing backer rod in the sealant joints is an essential step. Neglecting to do this can cause splitting, as movement can cause sealant or caulk to pull away from the gap.
There is a large selection of backer rod materials available for chinking and caulking applications. Log homes come in various shapes, each one having its own distinct characteristics. Backer rods are available in several types and are designed for specific uses. Common shapes include triangular, trapezoid, and round varieties. Backer rods come in various sizes and lengths to be used in conjunction with log home construction. Depending on the size and shape of the gap or void, the appropriate backer rod size must be chosen accordingly to control sealant depth. This means that once inserted, the backer rod is inset roughly 3/8" from the wood's surface.
Inserting backer rod is a straightforward process. Choose the right size and material and either push it into the gap or void by hand or use a tool like a backer rod inserter kit. The friction between the wood and foam should be enough to hold it in place, but you can use adhesive if necessary, just make sure it's only on the backer rod. After installation, be sure to leave around a 3/8" depth from the wood's surface to apply the chinking. Be careful not to press the backer rod too hard since it may cause wrinkles that will show on the chinking's surface.