Hot Topics: What's Wrong With This Shower Pan?

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Can’t figure out why your shower is leaking? Good thing you took some before pictures while your “plumber” was doing his repair, because the leak’s still going, he’s long gone and you need to find out where the water’s coming from. The Forum’s got the answer, but you might not like it.

Original Post: Shower Stall Leak

Binks1 Member

I have a 4x4-foot tiled shower stall in a pre-war New York City brownstone. This shower stall has given me nothing but problems. It leaked in the past to the point where the ceiling fell down in the apartment below mine. The plumber said the drip pan was bad so I had a brand new drip pan, drain pipe, flooring and tile installed by a licensed plumber. Within a year, it began to leak again to the apartment below. A plumber from the building management came and did a few tests like running the water, checking pipes by capping the shower head and running it, plugging the drain and filling up the stall with water. He suspected the drip pan was the issue, as a tiny bit of water came down but not enough to say the pan was bad. There were also some minor cracks in the grout just outside the shower, so he said this was also a possible source of if the shower curtain dripped outside the shower and water found its way down through those cracks. I had them sealed with silicon and we ran the shower for a week before having the ceiling below patched up and no water leaked during this time. It was fine for about 5 months. Now the leak started yet again, but there are no cracks and the tile and grout look fine. Also, when the shower is on, we are making sure no water fills up in the stall. Is it possible for a new drip pan less than 2 years old to leak? Could it be the pipes or something else? Any ideas or suggestions would help.

I attached a picture of the drip pan that was installed recently, it looks like it was done correctly so no idea how it could be the source of the current shower leak.

Highlights from the Thread

czizzi Member

The caulking goes underneath the membrane and seals to the bottom side of the shower drain assembly. Your caulking is on the top side of the membrane and blocks the drain holes. It also does not seal between the bottom to the drain body and the underside of the membrane to create a water tight seal. Review the following to demonstrate what I am saying. How to build a shower - Building a shower pan with pre-sloped mortar bed, liner and curb. You should not see any caulking on the visible side of the membrane.

PJmax Forum Topic Moderator

Not to hijack this thread... but a question for czizzi. I enjoyed that link you left above. Very informative. The question I have is that looks like a lot of work. Any opinions on the pre-pitched shower floors I've seen them use on TV shows? They look like fiberglass or some kind of HD foam.

a tile guy Member

I would never install a pan this way. First, why did he leave the lead pan then put the liner on top of that? He didn't go up the wall far enough, and doesn't look like there’s enough material to overlap the (questionable) wood curb. His repair joint is right on a tile joint; it should be in the middle of the tile. He has no room for metal lath or cement board to be nailed (too close to water line, he should be at least a foot above). Is there a preslope under the new pan? As czizzi pointed out, the drain is done all wrong, along with the new membrane. The curb needs to be redone also.

czizzi Member

PJ - Every shower stall is different, trying to by "off the shelf" slopes and then modifying is a waste of money IMO. I take a 2x2 or 2x4 and rip it down to the exact dimensions I want that fits the shower exactly. I cut 4 that radiate into the corners and 4 that radiate to the side walls. I do this twice, once for the pre-slope and once for the floor mud on top of the membrane. I pack the floor mud around the custom wedges, use them as guides to shape the floor, remove when the main floor is done and fill in between where the wedges were.

PJmax Forum Topic Moderator

Thanks for the info. This isn't my field and I didn't realize how labor intensive and involved it is.

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