A common problem with many log homes is gaps between log courses. Over time, as moisture slowly evaporates from the logs, they shrink and create gaps. These gaps can cause drafts that reduce energy efficiency. They allow moisture to collect between logs increasing the possibility of decay and create entry points for all kinds of wood boring or nesting insects.
Many log homeowners purchase silicone to caulk areas that have large gaps. In many cases there is a good possibility that this will fail. Sometimes this situation may be even worse than doing nothing at all because moisture will enter openings in the failed caulking and will not evaporate as quickly. This will greatly increase the likelihood of decay and insect problems.
Some common elements are essential for caulking success. First, you should select a caulking specifically designed for log homes. The logs should be free of dirt and oils. One of the most important elements of caulking is the use of backer rod in the log joints. Backer rod acts as a filler and insulator which reduces the amount of caulking necessary. But most importantly backer rod will allow the caulking to adhere to two points, the log above the joint and the log below. The caulking will not adhere to the backer rod. This allows the caulking to stretch like a rubber band. Without backer rod the caulking will adhere to the top and bottom log plus the area inside the joint. This is called three point adhesion. If the gap expands it is very likely the caulk or substrate (the log surface) will fail.
So, what can you do if you have a milled, chinkless log home with drafts and gaps between your logs? First, your logs need to be cleaned. If you know what finish is on your logs you should contact the caulking manufacturer for compatibility. Most finishes are compatible. If you do not know the finish, you can test the caulk with your existing finish or have it stripped, followed by a borate application then re-stain with a compatible stain. Once the logs are ready you can begin caulking using a backer rod wherever possible. If some gaps are too small to accept backer rod, it is acceptable to caulk assuming the logs have had adequate time to settle.
Whether you plan to caulk yourself or hire a log home professional this will greatly increase energy efficiency while eliminating water and insect infiltration. You can find very helpful information on many different websites from professionals or manufacturers of log home caulking products such as Sashco and Permachink. The benefits will be well worth the time and money spent.