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Why Does My Tub Caulk Keep Cracking and Peeling?
Short answer
Tub caulk that fails within months usually has one of four causes: new caulk was applied over old residue, the joint wasn't fully dry, the product wasn't 100% silicone, or the tub is moving when it's filled. Fixing the cause matters more than the next tube.
Leftover residue
This is the most common reason. Old silicone leaves a thin film even after the bead is gone, and a new bead sitting on that film peels in strips. If your failed caulk comes away in one clean rubbery ribbon with almost nothing stuck to it, adhesion was the problem. See why caulking over old caulk fails.
A joint that wasn't dry
A joint can look dry on the surface and still hold water in the gap behind the tub lip. Silicone won't bond to a wet surface, so a bead put on the same morning as a shower is at a disadvantage. Fans and time solve this one.
The wrong product
Acrylic and siliconized acrylic shrink and harden in a wet joint. If your failed bead was hard and brittle and cracked across its width, the product is the likely cause. Read our comparison of silicone and acrylic caulk.
A tub that moves
Acrylic and fibreglass tubs flex under the weight of water and a person. If the tub wasn't set in a mortar bed or wasn't well supported, it can move enough to tear the bead along the wall. A common installer trick is to fill the tub partway before sealing, so the bead cures with the tub already in its loaded position. Stand in your tub and press on the bottom with your foot: noticeable movement or creaking suggests support is part of the problem.
Water it shouldn't have seen
Showering in the first 24 hours is a classic cause, and so is heavy scrubbing with abrasive pads. See how long to wait before showering.
When it's something bigger
If the gap keeps widening, or the wall tiles shift when you press them, the framing or backing behind the tub may be the real issue. New caulk won't fix that. Caulk Control jobs in Kitchener, Waterloo and Cambridge carry a 12-month workmanship guarantee against peeling, lifting and separating under normal use, and if we find a soft or rotted wall, we stop and you aren't charged.