Leaks From Tubs

House Doctor | Gary Dymski

July 19, 2001

Q. Everyone in my neighborhood seems to have problems with leaky, second-floor bathtubs. The leak from ours ruined the kitchen ceiling and floor. At one time, a builder told us that the tub was not supported properly. The theory is that when a person stepped into the tub the caulking pulled away from the wall. This allowed the water to leak through the wall and down to the ceiling above the kitchen. We've had the tub floor reinforced, but it didn't help. We still have to recaulk every three months or so. What can we do?

-Caroline La Scala, Oakdale

A. Since you've already had the tub floor reinforced, I'm going to guess that the problem is with your tub wall rather than the tub floor.

You might have a tub wall that was lined with greenboard instead of a cement backerboard. It could be that the grout around your tile is starting to break down and water is seeping through the grout line and greenboard, down the wall and onto the ceiling below. Remember: Never use greenboard on a tub or shower wall. Greenboard is not waterproof.

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Inspect your tub wall. Are there any tile pieces so loose you can pull them off the wall? Can you see where grout lines are worn or breaking away from the tile? If so, these breakdowns can allow water to get behind the wall.

I have a shower wall in my 4-year-old home that needs to be replaced; my builder used greenboard on the wall and I didn't catch it. My mistake, and I have to pay for it by replacing the wall with cement backerboard and installing new tile.

As for recaulking, I routinely recaulk the line that separates the wall from the top of the tub or shower pan about twice a year. That caulk wears quickly; my experience is that removing the old bead and replacing it makes for a watertight seal.