Caulking is one of the least glamorous parts of maintaining a building and one of the most consequential. It seals joints and cracks against water, air, dust, insects and noise, and when it fails the damage usually shows up somewhere else entirely, as a stain, a draught or a corroded fixing.
What good caulking has to do
For a joint to perform, the caulk must adhere firmly to both sides of it and stay flexible enough to accommodate movement over time. Those two requirements pull against each other, which is why the product and the joint design matter as much as the application.
It is worth separating two terms that get used interchangeably. Sealants are engineered to seal joints that experience movement. Adhesives are used to restrict movement in joints. They are not substitutes for one another.
The most common cause of failure
When retrofitting caulking systems, whether masonry control joints, stone-to-stone joints, precast connections or concrete joints, complete removal of all existing caulk is critical. That includes any residual film along the joint edges.
One of the most common causes of failure in recaulking projects is applying new caulk over remnants of the old material. It is especially critical when moving from urethane or acrylic caulks to silicone-based products. Some manufacturers permit partial removal with the use of primers. Our experience is that full removal significantly reduces the risk of failure and gives far better long-term durability.
Two-sided adhesion
To achieve proper two-sided adhesion we install backer rods or bond breaker tape. This prevents three-sided adhesion, where the caulk bonds to the back of the joint as well as the sides and tears itself apart as the joint moves.
Read more about our caulking and sealant services, or ask us to look at a joint.
