Shower Waterproofing in a Condo or Co-op Bath: What the Board Wants to See Before Tile

Why boards care about what goes behind the tile

Boards care about shower waterproofing because once tile is set, nobody can see whether the shower was built watertight, and in a stacked building the unit below shares that risk.

Tile and grout are the wear surface, not the waterproof layer. The membrane behind them does the real work, so good practice is to prove the shower holds water before it's closed up.

Every building is different. Ask management whether your building has written waterproofing requirements.

The five things a board usually wants to see before tile

Many boards look for five things before tile: a rated membrane that runs continuously, a floor sloped to the drain, sealed openings, a water test that holds, and photos that prove it.

1. A continuous waterproofing membrane rated to ANSI A118.10

A membrane is a waterproof layer (a sheet or a brushed-on liquid) under the tile on the shower floor and walls.

ANSI A118.10 is the American National Standard for load-bearing, bonded, waterproof membranes used under thin-set tile. ANSI A108.13 sets how those membranes get installed. Both come through the Tile Council of North America (TCNA).

"Continuous" means no gaps at seams, corners, niches, benches, or the curb, and a drain tie-in done the maker's way. Use one system with the maker's own parts, not a mix-and-match. Wall height follows the maker's guidance and any building rule.

We build our showers with Schluter Kerdi: the Kerdi membrane and Kerdi shower pans, used together as one system. Schluter's data sheet lists Kerdi as meeting ANSI A118.10.

2. A shower floor that slopes to the drain

Model plumbing codes call for site-built shower floor liners to slope toward the drain at about 1/4 inch per foot (2 percent) and turn up at least 2 inches above the finished threshold.

Your local code and the membrane maker's instructions set the exact details. Permits as required.

3. Sealed openings: valve, shower head, niches, and the drain

Every pipe and fixture that passes through the membrane has to be sealed with the maker's parts: pipe seals, collars, and a bonded drain flange.

Plan door and grab bar mounts so extra screws don't go through the waterproof layer. Caulk is upkeep, not waterproofing.

4. A water (flood) test before any tile goes on

A flood test means plugging the drain, filling the shower floor with water, and leaving it to show it holds, after the membrane cures.

• Model plumbing codes set a minimum for site-built shower liners: at least 2 inches of water at the threshold, held at least 15 minutes.
• Membrane makers often recommend more, sometimes 24 to 72 hours.
• Schluter, the maker of Kerdi, says a water test is "strongly recommended before setting tile." If the marked water line holds, it passes.

We flood test every tiled Kerdi shower before tile, following Schluter's guidance: we wait at least 24 hours after the membrane goes in, then hold water in the pan for about 24 hours.

If your building wants the ceiling below checked during the test, tell us at the walk so management can set up access.

5. Dated photos before tile hides the work

Once tile is up, photos are the only proof of what's behind it. We set up GoPro cameras and record every bathroom job in timelapse, and the footage goes to the customer, so the waterproofing step is on record before tile hides it. If the owner wants the board to see it, the owner can share the footage.

We take photos of the waterproofing before tile. They're available to the owner or manager on request, alongside the GoPro timelapse footage we give the customer.

Questions about your building? Call or text (267) 463-8138.

How to ask for this when the board reviews the plan

The easiest approvals happen when the plan names the membrane system, shows how the hard spots get sealed, and says when the water test and photos will happen.

• Which membrane system, and does it meet ANSI A118.10?
• Will it run continuously on the floor, walls, curb, and niches?
• How are the valve, shower head, and drain sealed?
• Will there be a water (flood) test before tile, and who can see it?
• Will we get dated photos before tile?

For the rest of the building checklist (sign-off form, insurance papers, hours, elevator, shutoffs), see our condo and co-op remodel guide.

Where the shower checkpoint fits in an occupied-unit bath remodel

The waterproofing checkpoint sits after demo and plumbing rough-in and before tile, so it belongs on the schedule the board sees before day one.

1. Walk the unit, then written scope.
2. Building rules, elevator, hours, and shutoffs set with the desk.
3. Demo and rough-in. Permits as required.
4. Kerdi pan and membrane, a 24-hour minimum wait, a flood test of about 24 hours, and photos. This is the board's checkpoint.
5. Tile, fixtures, paint, daily cleanup.

A shower surround can go quickly. A tiled shower with a Kerdi pan can take about 5 to 8 days, depending on size, complexity, and building rules or access limits. You get the full schedule after we walk the unit.

Related: hall bath questions, occupied kitchen questions.

Bath packages for condo and co-op units

Most shower work in a condo or co-op falls under our hall bath gut ($15,000–$30,000) or primary bath ($25,000–$55,000) package.

Other packages: kitchen ($35,000–$70,000), rental kitchen ($25,000–$45,000), and basement ($25,000–$65,000). Materials included. Ranges finalize after we walk the unit. Full package ranges and FAQ.

Buildings we've worked in

Buildings we've worked in include Residences at Dockside (bathrooms), Siena Place, 511 Condominium Residences, William Penn House (a co-op), and Bridgeview Place Condominiums.