Shower pan flood test before tile

The adopted plumbing code, local amendments, manufacturer instructions, and AHJ determine whether a flood test is required, how it must be witnessed or documented, and the required water depth and hold time. Do not substitute a quick hose spray for a required standing-water test.

Review the permit card, inspection request, correction notices, and product instructions before filling the pan. Confirm the waterproofing has reached the manufacturer's required cure or set time and that tile, setting bed, curb finish, or other cover-up has not hidden the receptor test area.

- Installer uses an internet default for test duration instead of the local code or AHJ requirement

- Flood test starts before a liquid membrane, thin-set seam, hot mop, sealant, or bonding flange has cured enough

- Inspector is called after tile or a mortar bed hides the pan liner condition

- Prefabricated or bonded waterproofing system is assumed exempt without checking manufacturer and AHJ requirements

A site-built receptor liner, bonded sheet membrane, liquid-applied membrane, hot mop, foam tray assembly, or other approved system should be installed as a complete waterproofing assembly before testing. Seams, corners, curb transitions, jamb returns, penetrations, and drain tie-in must follow the listed system and manufacturer instructions.

Inspect the pan, curb, inside corners, outside curb corners, jambs, floor-to-wall transitions, and drain area before water is added. Look for full membrane coverage, required reinforcement fabric, sealed overlaps, bonded corners, intact hot mop or liner, and no unapproved cuts or fasteners in vulnerable locations.

- Fasteners or staples placed through the liner below the allowed height

- Liquid membrane applied too thin, with pinholes, holidays, or missing fabric at changes of plane

- Sheet membrane seams or preformed corners not fully bonded

- Curb top or outside curb corners left unsealed before the test

- Backer board or blocking hides a liner fold, cut, or low fastener

The waste line must be plugged watertight in a way that includes the receptor-to-drain waterproofing connection in the test. Traditional clamping drains, weep-hole drains, bonding flange drains, linear drains, and proprietary drains each need the plug location and method allowed by the product instructions and AHJ.

Identify the drain type before placing the plug. Confirm the plug does not sit above the waterproof connection in a way that leaves the critical drain tie-in untested. Fill the drain body first to check that the plug itself is watertight before filling the receptor.

- Tape, a rag, or a loose stopper is used instead of a proper test plug

- Plug is set above the clamping flange or bonding flange, so the drain connection is not actually tested

- A leaking test plug is mistaken for a failed pan

- Weep holes or drain channels are packed with debris before the test

The test water level must meet the adopted code, manufacturer, and AHJ requirement without overflowing into adjacent construction. Curbless and low-threshold showers commonly need a temporary dam accepted by the AHJ and compatible with the waterproofing system.

Check the curb, threshold, or temporary dam before filling. It should be braced, sealed, and removable without puncturing or tearing the membrane. Confirm the planned water level will reach the intended test height at the threshold while staying safely below overflow points outside the shower.

- Temporary dam is taped to dusty or uncured membrane and leaks at the floor

- Screws, nails, or clamps puncture the waterproofing while holding the dam

- Water level is too low to test curb corners or jamb returns

- Curbless shower is tested without a dam even though the AHJ expects one

The receptor should hold the required standing water level for the AHJ, adopted code, and manufacturer-required test period with no evidence of leakage. Exact depth and duration are local and system dependent, so record the requirement instead of assuming one generic number.

Fill from a clean water source to the required level, let the water settle, then mark the level on tape, the temporary dam, or another stable surface. Photograph the starting mark and ending mark. Do not refill, drain, step in the pan, or use nearby fixtures in a way that can disturb the result.

- No start mark, so the end level cannot be verified

- Water is topped off during the test, hiding a slow leak

- Splashing, evaporation, or a moving dam is not distinguished from leakage

- Someone removes or bumps the plug before the required hold is complete

A passing flood test means no evidence of leakage at the receptor, curb, jambs, floor outside the shower, ceiling below, crawlspace, basement, subfloor, framing, or drain and waste connection visible from below.

During the test and before draining, inspect below and around the shower where access exists. Use a flashlight at the ceiling below, open framing, crawlspace, adjacent closet, curb exterior, and bathroom floor perimeter. Check again after some time has passed because slow leaks may show up late.

- Leak appears at the ceiling below only after water has been standing for a while

- Curb exterior or jamb gets wet while the pan still appears full

- Water follows the drain pipe or framing and shows up away from the shower footprint

- Dampness is dismissed as construction moisture without a photo or recheck

Do not cover the receptor with tile, setting bed, curb finish, lower backer-board cover-up, or other work that hides the test area until the required flood test has passed and any AHJ or manufacturer documentation is complete. Failed areas should be repaired, cured, and re-tested before cover-up.

Save photos of the product labels, drain type, test plug, water-level start and end marks, threshold or temporary dam, visible underside, and AHJ sign-off or affidavit where used. After draining, confirm the membrane is not blistered, delaminated, cut, or damaged by plug removal and that the drain path is clear for the next trade.

- Tile work starts after a patch but before the repair has cured and been re-tested

- No photo shows the water level at both start and finish

- Plug removal tears the membrane or disturbs the drain bond

- AHJ-required affidavit or inspection record is missing at final approval