Shower Waterproofing Inspection

Shower waterproofing is the most critical element of a bathroom. Membrane must be continuous with no gaps. Substrate must be cement board or equivalent.

1. Ask for documentation/photos of waterproofing installation (should be done before tile)

2. Verify substrate is cement board, Kerdi board, or equivalent (NOT green board or regular drywall)

3. Check for membrane type: sheet membrane (Kerdi), liquid-applied (RedGard, Hydroban), or pan liner

4. Verify membrane extends up walls minimum 6" above showerhead height

5. Check that all joints, corners, and penetrations are sealed with waterproofing tape/fabric

6. Verify shower curb is waterproofed on all three sides (top, front, and behind)

7. Check for pre-slope under liner (traditional pan) — water should drain to weep holes

8. Verify drain connection to membrane is watertight

- Regular drywall or green board in shower (will fail — guaranteed water damage)

- No waterproof membrane behind tile (water penetrates grout)

- Membrane not covering curb (water seeps through curb)

- Corners and joints not sealed (water finds the weakest point)

- No pre-slope in traditional pan (water pools under liner)

- Drain not properly connected to membrane (water bypasses drain)

Shower pan must be flood-tested before tile. Plug drain and fill with 1-2" of water for 24 hours. No water loss indicates proper waterproofing.

1. Ask if a flood test was performed before tiling (24-hour test required by code)

2. If before tile: plug drain, fill shower pan with 1-2" of water, mark water level

3. Check after 24 hours — water level should not drop at all

4. Check the ceiling below for any moisture or staining

5. After tile: run shower for extended period and check for leaks below

6. Check shower door/enclosure for water containment

7. Verify caulk (not grout) at all change-of-plane joints

- No flood test performed (most common cause of shower leaks discovered after move-in)

- Water level drops during test (leak in membrane or drain connection)

- Moisture on ceiling below (active leak)

- Grout used at floor-to-wall joint instead of caulk (cracks and leaks)

- Shower door not properly draining back into shower

- Missing caulk at fixture penetrations