Three-Sided Adhesion
A sealant bonded to the base of a joint as well as both faces, so it cannot deform freely as the joint moves.
On an actual building
It is the classic sealant failure, and it is entirely preventable with a backer rod. The sealant tears down its centre rather than at an edge, which is the diagnostic sign.
What we most often have to correct
That more adhesion is better. In a moving joint, adhesion to the base is precisely what destroys the seal.
Terms that come up alongside this one
- Backer Rod
A closed-cell foam rod pressed into a joint before sealant, setting the correct sealant depth and preventing it bonding to the joint base..
- Sealant Movement Capability
The percentage of a joint's width that a sealant can accommodate in extension and compression without failing, stated by the manufacturer..
- Expansion Joint
A deliberate gap through a structure that allows adjacent parts to move independently under thermal and structural movement..
Three-Sided Adhesion — questions we get asked
What does three-sided adhesion mean in waterproofing?
A sealant bonded to the base of a joint as well as both faces, so it cannot deform freely as the joint moves.
Why does three-sided adhesion matter on a real project?
It is the classic sealant failure, and it is entirely preventable with a backer rod. The sealant tears down its centre rather than at an edge, which is the diagnostic sign.
What do people commonly get wrong about three-sided adhesion?
That more adhesion is better. In a moving joint, adhesion to the base is precisely what destroys the seal.
Have a building showing this?
If a term on this page describes something you are looking at, a site inspection will tell you how far it has gone and what it needs. It costs nothing.
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