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What Causes Caulk to Fail and How to Fix It.

Sealants are one of the most effective and widely used building products and the most commonly misused. Below are a few common causes of sealant failure and easy ways to help prevent them.


What is cohesive caulk failure?
Cohesive failure is when the caulk line cracks or tears down the center.

Possible causes & solutions for cohesive failure:

caulking tips

Cause #1:
Caulk can fail when the bead sticks to the back of the joint and the side, and the caulk can’t stretch correctly. To avoid this, insert backer rod (foam rope) into any joint 1/4″ wide or larger.

As a result of extreme or sudden movement, caulk can get stressed on surfaces. It relieves itself by splitting down the middle. This is often the case with caulk applied indoors in the winter before the heat is turned on. When the heat is turned on, the surfaces move rapidly, stressing the caulk line and causing some splits.

Cause #4: Too little caulk applied

It is difficult to fit enough caulk into a tiny 1/8″ wide joint to adhere to its sides and leave enough in the middle so the joint can stretch. For example, when you apply a small 1/2″ bead to big round logs, the bead is too small to accommodate the shrinkage and movement these logs undergo. Be as generous as possible with how much caulk you apply.

For each example, the solution is the same: