How to Fix a Leaky Shower Drain – install the new rubber gasket, strainer body and seal the drain to the shower pan with silicone caulk.
This project is continued from How to Fix a Leaky Shower Drain – Part 6.
Leaky Shower Drain Repair
After disassembling the cleaning the shower drain, we inspected the drain body, strainer body and shower pan for cracks or broken parts. Finding no damaged parts we made a trip to Home Depot to buy a new drain because we needed a new black rubber gasket; you have to buy the whole drain just to get the gasket.
Here’s the shower drain cleaned and ready for reassembly:
Cause of Shower Drain Leak
Notice the fiberglass shower pan is approximately 3/8ths inch thick at the drain hole as indicated by the red arrows in the above photo. By comparison, my shower pan is about 1 inch thick at the throat. This is very significant because plumber’s putty is much more likely to squeeze out around the black rubber gasket on this homeowner’s thinner shower pan whereas on my much thicker shower pan, the plumber’s putty simply fills the void within the threads of the strainer- and drain body before it reaches the rubber gasket.
The homeowner confirmed the shower drain was originally installed by the home builder with plumber’s putty when it first started leaking. The leak was caused by aging and brittle plumbers that lost its “grip” over time (10 or 11 years) as the shower pan flexed from a person’s weight. This allowed the strainer body work ever so slightly loose, relieving compression on the black rubber gasket and thus began the water leak.
When the homeowner attempted to repair the shower drain, he used an excess of plumber’s putty which squeezed out around the rubber gasket, interfering with it’s function and pushed the gasket off center. The other problem with plumber’s putty is it continues to squeeze out over time because it’s packed against the rubber gasket, relieving the pressure on the gasket and the shower drain leaked.
The purpose of plumber’s putty isn’t to make a watertight seal when applied to the shower drain, rather it’s prevent the strainer body from unscrewing and relieving pressure on the rubber gasket – think of plumber’s putty in this application as a “thread locking” agent.
The other way to install a shower drain is to seal it with silicone caulk. Sioux Chief is a manufacturer of shower drains sold by Home Depot which instructs to use silicone caulk instead of plumber’s putty. The silicone caulk keeps the shower drain tight.
Shower Drain Installation
The homeowner purchased a tube of GE Silicone 1 100% silicone caulk for bath/kitchen/plumbing at Home Depot with a new Sioux Chief shower drain. We used only the black rubber gasket and metal strainer from the Sioux Chief drain because the strainer body threads are incompatible with the Plastic Oddities PFG600 drain.
Insert the black rubber gasket between the shower drain body and bottom of the shower pan as shown in the photo below. Note the plastic anti-friction gasket was not installed because the homeowner will be in the basement holding the pipe from twisting as the strainer body is screwed in.
Apply a bead of 100% silicone caulk to the recessed rim of the shower pan drain hole. Do not use latex caulk because it can become brittle and is subject to attack by mold and mildew.
Next, screw in the shower drain strainer body until it’s hand-tight and firmly seated – however, it’s not yet tight enough! I used a large pair of channel locks against the two inside nubs to tighten it an extra 1/2 to 3/4ths turn or so to compress, but not crush, the black rubber gasket for a watertight seal. Wipe off the excess silicone caulk.
A new metal strainer is installed and fastened with two screws. Be careful not to drop the screws down the drain.
Shower pan bottom and shower drain after reassembly:
Drywall Ceiling Water Damage Repair
Since the basement room was mainly used for recreation and storage, instead of an extensive drywall repair, I suggested a plastic access panel to cover the hole in the drywall ceiling as a quick and easy way to cover the damage. A 9in x 9in Watts SpringFit Access Panel at the local hardware store was the closest size and has the benefit of fitting over jagged holes. The SpringFit has a spring-loaded tongue on back that automatically adjusts to fit a wide range of openings.
The Watts SpringFit access panel is test fitted over the jagged hole in the ceiling. The homeowner will install a thin wood reinforcing strip above the ceiling to provide reinforcement and backer for drywall spackle to fill the small gap on the left. Now only light spackling and sanding is needed before painting.
See How to Fix a Leaky Shower Drain – Part 8 for a new shower drain repair issue sent in by a HandymanHowTo.com reader.
Hope this helps,
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