Shower pan leaking to the floor below

Symptoms

• Stain or drip on the ceiling below the bathroom
• Soft or spongy flooring near the shower
• Musty smell in the room below
• Grout or caulk around the shower base looks compromised

Likely causes

• CommonFailed caulk seal where the pan meets the wall or drainSmall gaps let water seep underneath during every shower rather than draining properly.
• PossibleCracked shower pan or linerFiberglass or acrylic pans can crack with age or if something heavy was dropped on them.
• PossibleFailed drain seal or gasketThe connection between the drain and the pan can loosen or the gasket can degrade over time.
• Less commonDeteriorated waterproof membrane under tile shower floorsTiled showers rely on a hidden liner beneath the tile that can fail without visible surface signs.

What to do

1. Stop using the shower until the source is identified, since continued use will worsen hidden damage.
2. Inspect all caulk lines around the shower base and drain for gaps, cracking, or peeling.
3. Remove and replace any suspect caulk with fresh waterproof silicone.
4. Check the drain assembly for a loose fit or visible gap around the strainer.
5. Run water briefly and check the ceiling or floor below immediately after to see if the leak recurs.
6. If the leak continues after resealing, the pan liner or drain gasket likely needs replacement, which typically means removing some tile or the pan.
7. Document any ceiling staining with photos before repairs in case of insurance or resale disclosure needs.

Tools and parts

• Utility knife
• Caulk gun
• Flashlight

When to call a pro

Call a licensed plumber or contractor if the leak persists after resealing, since it likely means the pan or membrane needs replacement, a larger repair involving tile removal.

Safety