Backer Rod and Chinking Part 1 & 2
Part 1
As the warm weather begins, its the time of year when we start thinking about chinking our log homes. The first step of caulking or chinking is applying Backer Rod. The *Log Core will take you through a two part series of Backer Rod and Chinking. We will begin this series with backer rod of all types.
Backer Rod is a synthetic foam that comes in a variety of shapes and sizes from 1/4" up to 5". The reason why Backer Rod needs to be placed in joints is that it acts as a bond breaker, which provides a surface that chinking won't adhere to. Eventually, the chinking will free itself from the backer and will move with the logs as they expand or shrink. Backer Rod also serves by adding an insulation value and reduces the amount of material needed.
Grip Strip backer rod provides an excellent fit with a flat working surface and is a closed cell product that repels water. As a chinking applicator for a restoration company for 7 years in Northern Minnesota, I have found this material is the easiest and quickest to use. No tools are necessary and it follows with the curvature of the logs. This product really grips to the logs and stays in place.
SOF Rod can be described as an open cell, extruded polyethylene foam. SOF Rod is extruded to leave an impermeable shell to prevent moisture from entering the side. Advantages of this backer are that it is very flexible and is easy to install. Smaller sizes are offered to fit those really tight joints. When choosing a size, the diameter should be approximately 25% larger than the joint because of the compressibility. Precautions to take are not to puncture or stretch during application. This may cause out gassing. In smaller joints a blunt tool may be needed to push backer further into the joint to allow the required amount of chinking. This material is easier to work with for smaller size joints.
Closed Cell backer rod is a closed cell polyethylene round foam that also runs in a continuous length. Compared to the SOF Rod this backer is firm, but just as easy to install. Again a blunt tool may be needed to push backer deeper into the joint to allow the required amount of chinking.
Open Cell Backer Rod is easy to work with also. It is soft and compresses to fit most size joints. This product is breathable which allows for a faster cure, but recommended in the interior. This is because it will absorb water. If used on the exterior, only put in the amount of open cell that you think will get done in one day so the exposed backer will not draw in moisture. Note: the use of a blunt tool when installing backer rod to the exterior logs will prevent punctures to the surface of the rod and minimize chink blistering caused by trapped water vaporizing under direct heat from exposure to the sun.
For smaller joints where backer rod can not fit, but yet there may be a gap, a mylar tape or strapping tape may be used. This too will serve as a bond-breaker to allow the material to release itself from the tape and move with logs as they settle and shrink. If applying chinking over old mortar, a bond-breaker tape should be applied as well. Packing tape or duct tape are two examples that will work for this situation.
If the backer seems to keep popping out, a smaller backer or a different style of backer is needed. You should never have to nail Backer Rod to keep in place. The most common mistake about choosing Backer Rod is selecting a backer that is too big for the joint. When this happens, the backer keeps coming out or you are left with a chinked joint that is larger than it needs to be. I recommend to take advantage of the samples we have to try different styles and sizes. Keep in mind that you may require a number of different styles and sizes for your particular project.
*Backer Rod and Chinking Part 1 (courtesy of Denise Carlson, Schroeder Log Home Supply, Inc.)
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