Question: Why is my chinking and caulking tearing down the middle and how do I fix it?
The short and technical answer: cohesive failure. Here are the cause and solutions (just what you were waiting for!)
Cause #1: Three-point adhesion
The caulk bead is sticking to the back of joint, as well as the sides, which doesn't allow the caulk to stretch correctly. Avoid this by inserting backer rod (foam rope, widely available at hardware stores) into any joint that is 1/4" wide and 1/2" deep or larger.
Cause #2: Rapid or Extreme Movement
If the surfaces the caulk was applied to undergo extreme or sudden movement, it can cause the caulk to get stressed. It relieves that stress by splitting down the middle. This is often the case with caulk is applied indoors during the winter, before the heat is turned on. When the heat is turned on, it causes the surfaces to move a lot and quickly, stressing the caulk line and causing some splits. This is also very common on new log homes that are still acclimating to their new environment. On the interior, run a humidifier to help reduce the rate at which the logs dry out.
Cause #3: Caulk Not Allowed to Properly Cure
Caulk applied in freezing temps or hot temps can't properly cure and form all of its necessary chemical crosslinks that allow it to stretch and adhere correctly. Be sure to carefully follow the manufacturer's application instructions where it states the type of temps you need during application.
Cause #4: Too little caulk applied
A tiny 1/8" wide joint does not accommodate enough caulk to both adhere to the sides of the joint and leave enough in the middle the stretch properly. Or, as is the case with big round logs, a small 1/2" bead isn't wide enough to accommodate the shrinkage and movement those big logs undergo. Try to apply enough caulk from the get-go, but understand that there may be some repairs to do when you can't. With chinking in particular, we always recommend a chinking width that is at least 15% of the log diameter. If you prefer something more narrow, just be prepared to do repairs, especially early on.
Finally, how do you fix these tears and splits?
Thankfully, repairs are easy.
Where the caulk has split, release the pressure by slitting open the tear with a razor blade. Where possible, insert backer rod. It should always be used in any joint 1/4" wide or wider and 1/2" deep or deeper. If you couldn't fit it in before but the joint is now big enough for backer rod to fit, put some in.
If your caulk will stick to itself, simply apply more caulk over the existing bead. All of Sashco's products will stick to themselves, making repairs quick and easy. Some products can't do that. In particular, silicone won't stick to itself (and nothing will stick to silicone). In these cases, you'll have to completely remove the caulk and start over. Check with the manufacturer to see if their product can be repaired with more of the same.
Published on: May 3rd, 2018
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