Shower Enclosure Leaks at the Glass and Curb

Why glass enclosures leak in the first place

A frameless or semi-frameless glass shower enclosure relies on a few small parts to keep water inside the shower: a bottom sweep or seal at the base of the door, silicone caulk where the glass meets the curb or wall, and sometimes a magnetic strip where two glass panels meet. Any one of these can fail on its own. Silicone shrinks and cracks with age and heat cycling. A door sweep wears down from being dragged open and closed thousands of times. A hinge that's slightly out of adjustment lets the door hang a few degrees off, which means water hits the seal at an angle it wasn't designed for. None of these failures are dramatic. They just mean a small amount of water gets past the barrier every time the shower runs, and that water has to go somewhere.

The curb is doing more work than it looks like

The shower curb, the raised lip you step over to get in, is supposed to be sloped and sealed so water runs back toward the drain instead of over the edge. When the caulk between the glass and the curb cracks, or when the curb itself was built without a proper slope, water starts tracking along the top of the curb and finding the grout lines or the seam where the curb meets the bathroom floor tile. This is a slow process. It might take months of small overflow before enough water gets underneath the tile to reach the substrate. That's part of why this kind of leak is easy to miss: the shower still looks fine from the outside long after the damage has started underneath it.

What rotted framing actually looks like once you find it

Bathrooms are usually framed with standard dimensional lumber, and that wood is not designed to handle repeated exposure to moisture. Once water gets past the curb or the wall assembly behind the tile, it can sit against the studs and sill plate for a long time before anyone notices anything on the surface. Signs to look for include a curb that feels slightly spongy or gives when you step on it, tile that has started to crack or feels loose even though nothing hit it, a bathroom door or nearby flooring that no longer sits flush, or a musty smell that doesn't go away with cleaning. By the time wood framing is visibly discolored or soft to the touch, the deterioration has usually been present for a while, and it rarely stays contained to just the one stud or section it started in.

Checking your own enclosure before it gets worse

You don't need special tools to do a basic check. Run your hand along the bottom door sweep and look for gaps, cracking, or a sweep that's pulled away from the glass. Look at the caulk line where the glass meets the curb and the walls; if it's cracked, yellowed, or you can see a gap you could slide a fingernail into, that's a point where water is getting through. Step on the curb itself and see if it flexes. Check the grout on the curb top and the floor just outside the enclosure for cracking or discoloration. If you find one of these signs, it doesn't necessarily mean the framing is already compromised, but it does mean water has a path, and that path only gets used more over time, not less.

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