I must have a bit of Home Inspector in me because I look around at everything when I enter a room, including the ceiling. This is why I noticed a water stain on the drywall ceiling of the game room in the finished basement. I asked the kids and wife who frequent the game room, “How long has that been there?!” They replied, “Oh, we never saw that!”. Sigh – they probably wouldn’t have noticed the water leak until the ceiling fell in.
Water Stain on Ceiling
Time to get the ladder and flashlight to find the source of the water leak.
Finding the Leak
Working on a ladder with a flashlight, I quickly traced water leak to the shower drain plumbing below the master bath. Water is dripping from the U-bend below the shower 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. Note: You cannot walk on the suspended drywall ceiling! It won’t support you and you will fall through!
Water Leak from the Shower Drain Plumbing
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.
Shower Drain Plumbing
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.
Closeup of Shower Drain Body and Water Stains
A dusty-white evaporation trail from the shower leak is visible on the floor joist to the left.
Whitish Water Stains on the Floor Joist
Now that I’ve identified the source of the water leak, how do I fix it?!
Understanding a Shower Drain
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 better show how it fits into the drain body:
Solvent Weld Shower Drain
This next diagram shows how the shower drain is assembled and fits against the shower pan. My shower is leaking between the shower pan and rubber gasket. Click on the image for a larger view.
Shower Drain Installation Diagram
My drain is a “solvent weld” model, meaning the drain body is glued to the PVC pipe with PVC primer and glue.
Bottom of Shower Drain and 2-inch PVC Pipe
This repair is continued in Part 2.
Regards,
Bob Jackson
July 3rd, 2009 at 3:56 pm
Thanks for the information. Easy to fix if you know what to do. My drain leaked due to the plumbers putty drying out after being gone for two weeks. A nice way to come back from vacation.