How to fix a leaky shower drain by tracing the water stain on the ceiling to the shower, take apart the drain and replace the cracked shower drain body and rubber gasket.
How to Fix a Leaky Shower Drain
I noticed a water stain on the drywall ceiling in the finished basement. I’ve learned to always look at the ceiling when I walk into a room because I’ve had other shower leaks – see How to Fix a Shower Leak Behind the Wall. The copper water pipes and PVC drain plumbing runs under the floor joists in the ceiling crawlspace, so something must be leaking. Time to get the ladder and flashlight to find the leak.
I quickly traced water leak to the shower drain plumbing below the master bath where water is dripping from the U-bend onto the basement ceiling. I placed an aluminum pan on the under the U-bend to catch the drips. This is the view of the crawl space between the basement ceiling and main floor of the house. It’s not possible to walk or crawl on the suspended drywall ceiling because the drywall won’t your weight and will break.
Aside: Also see this related article for cutting an access panel in the drywall to diagnose and fix a leaking shower arm on the fresh water supply side.
I worked my way around the crawlspace to get a better view of the shower drain. Water stains are evident around the drain body, plywood subfloor and floor joist.
Here’s a closer look at the leak source around the shower drain body. The water leak is between the drain body and bottom of the shower pan.
A dusty-white evaporation trail from the shower leak is visible on the floor joist to the left.
Now that I’ve identified the source of the water leak, how do I fix it?!
Shower Drain Installation Diagram and Parts
Shower drains are made somewhat differently depending on the construction of the shower pan, either a preformed pan or a pan that is built on-site with a vinyl liner over a mortar bed. The Sioux Chief Mfg Co. has a nice range of screw on, snap-in, no-caulk, modular, etc shower drains. For an overview of a shower drain for a tiled shower pan with a vinyl liner, click here.
I have a preformed fiberglass shower stall in the master bath that has a modular screw-in solvent-weld shower drain like this model by Sioux Chief.
Here the drain strainer body is removed to show how it fits into the drain body:
This shower drain installation diagram shows how the shower drain is put together and installs against the shower pan. My shower is leaking between the shower pan and rubber gasket. Click on the image for a larger view.
My drain is a “solvent weld” model, meaning the drain body is glued to the PVC pipe with PVC primer and glue.
This repair is continued in How to Fix a Leaky Shower Drain – Part 2.
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