Caulking Gaps Between Log Courses

Gaps between logs - a common problem with many log homes
Over time, as moisture slowly evaporates from logs in a wall, they can 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 rods in the log joints. A backer rod acts as filler which reduces the amount of caulking and acts as an insulator. But most importantly a 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 a 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.

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 a backer rod, it is acceptable to caulk assuming your log home has had adequate time to settle.

Caulking is a good investment
Whether you plan to do the work yourself or hire a log home professional caulking your log home will greatly increase energy efficiency while eliminating water and insect infiltration. You can find very helpful information on many different websites from log home professionals or manufacturers of log home caulking products such as Sashco and Perma-Chink. The benefits will be well worth the time and money spent.

Tom Tydeman
Log Options, LLC
www.logoptions.com

(Diagram from Schroeder Log Home Supply, Inc. website)