Published on June 5th, 2013 | by Henri


Slow leak through old shower pan

Q.    I am plagued with a leaky shower in the second-floor master bath. It leaks onto the family room ceiling located below the master bath. It is a small leak; nonetheless still a problem.

I have had numerous plumbers to look at it.  Some don’t know while others don’t want to be bothered. I opened up the area in the ceiling with the water stain; therefore, I can now see that the water is dripping down an electrical wire onto the drywall ceiling beneath it.

I now understand the pattern of the stain on the ceiling, and the trail it follows after it drips from the electrical wire onto the dry wall. It takes the water about 45 minutes to actually leak after the shower has been turned off. It’s only a drop or two. (One of the plumbers checked the drain. It is OK. He thinks it might be the grout, though it’s not that bad.)

Also, I have re-grouted the shower pan. I have not used this shower for about three years. I would like to close the hole, paint the ceiling, and use the shower if I could solve this mystery.

A.    You don’t say but I am assuming your house is 35 or more years old. Assuming that a lead or composite pan was properly installed under the floor tiles, this type of leak usually comes from deterioration around the Josam drain.

Since grout is not waterproof, water seeps through to the pan where the minerals in the water cause corrosion around the drain. It takes a long time for the leak to show up because water has to seep through the grout and the mud bed onto which the tiles are set.

The solution is to replace the entire pan with a fiberglass one. I am surprised none of the plumbers you called mentioned that possibility; they may be too young in the profession to have encountered this problem which was common in the ’50s and ’60s when most shower pans were built that way.

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