Usually caused by cracked plumbers putty or too much flex in the fiberglass tub due to lack of support If you’re experiencing problems with your shower drain, don’t despair 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.
Shower drain leak repair - YouTube
Here are the steps to repair a shower drain leak without replacing pipes
Remove the shower drain cover and inspect the drain flange
The leak is likely coming from the gasket/seal under the flange 1 use an exacto knife or scraper to remove any old putty or caulk around the flange 1 if the drain flange is loose, try wiggling and pulling it out Say goodbye to water damage for good!