Shower waterproofing: what goes behind the tile
Guide · Updated
The part of a shower you never see decides how long it lasts. Here is how showers are waterproofed, and how we do it on every Nomi shower.
Tile is not waterproof
Tile and stone resist water. The grout, the seams and the wall behind them do not.
A home is built in layers. Water that gets past the tile reaches the board, the studs and the floor under the shower. Nobody sees it for months. By the time there is a stain, a loose tile or a musty smell, the damage is behind the wall.
That is why a shower has to be waterproofed behind the finish, on the floor and on the walls, before any tile or slab goes up.
Three ways a shower gets built
Most showers are built one of three ways. They look the same on day one. They do not age the same.
| Method | What it is | Who uses it |
|---|---|---|
| Green board | Moisture-resistant drywall. Resists water, is not waterproof. | Many one-day and acrylic shower systems |
| Liquid membrane | A thick coating rolled or brushed onto the wall. | Many contractors, as the market standard |
| Sheet membrane system | A pliable waterproof sheet bonded to the wall and floor, with sealed seams. | High-end remodelers |
Green board
Fast and low cost. But moisture-resistant is not waterproof. Water can still get behind the walls over time, and that is where hidden mold grows.
Liquid membranes
Products like RedGard and Hydro Ban are rolled on as a thick, rubbery coat. They protect far better than green board, but only when the coat is the right thickness everywhere. A thin spot or a missed corner lets water through.
Sheet membrane systems
Systems like Schluter KERDI use a pliable sheet that is both a waterproof membrane and a vapor retarder, made for showers, tub surrounds and steam showers. The sheet has the same thickness everywhere, and every seam and corner is overlapped and sealed. It takes more time and skill to install.
How we waterproof a Nomi shower
We use an advanced waterproofing system on every shower floor and wall, never green board.
We take the wet area down to the studs. We rebuild the walls, then waterproof the floor and walls as one system before any tile or slab goes up. With stone slab walls, the slab itself is non-porous too.
A steam shower needs a vapor retarder on top of waterproofing, because steam pushes moisture into the walls. We plan it as part of the build. About steam showers
Signs your shower is leaking
Water behind the wall shows up slowly. Look for:
- Grout or caulk that keeps cracking
- Loose, hollow-sounding or cracked tile
- Mold that comes back days after you clean it
- A musty smell that does not go away
- Soft spots in the wall next to the shower
- Stains on the ceiling below an upstairs bathroom
Cleaning will not fix water that is already behind the wall. The fix is a shower rebuilt from the studs. About shower remodels · Black mold in the shower
Why it matters in North Texas
North Texas clay soil swells and shrinks with the seasons, so houses here move a little. Small movements crack grout and open seams. A waterproof layer behind the finish keeps a hairline crack from turning into a wet wall.
Every Nomi remodel carries a 2-year workmanship warranty. Our warranty
“All we did was choose the shower fixture, type of glass door and tile, NOMI took over the Project from there. Cost? exactly what they estimated. No surprises.”
Questions
Is tile waterproof?
No. Tile and stone resist water, but grout and seams let water through to the wall behind. A shower has to be waterproofed behind the finish.
Is green board waterproof?
No. Green board is moisture-resistant drywall. It resists water but is not waterproof, so water can still reach the wall over time.
What is Schluter KERDI?
A pliable sheet membrane that waterproofs a shower and works as a vapor retarder. It is made for showers, tub surrounds and steam showers.
How do you waterproof a shower?
We take the wet area down to the studs and waterproof the floor and walls with an advanced waterproofing system before any tile or slab goes up. We never use green board.
Can you waterproof my shower without removing the tile?
No. The waterproofing goes behind the tile, so the tile has to come off. A sealer on top of grout helps it stay clean, but it does not waterproof the wall.
How much does a shower remodel cost?
A shower remodel runs $15,000 to $25,000, in tile or in groutless Dekton slab. Design, labor and materials are all included. Most take 4 days in your home. About shower remodels
Where do you work?
Dallas-Fort Worth and the surrounding area, including Dallas, Fort Worth, Plano, Frisco, Southlake, Westlake, Highland Park, Prosper, and Addison.
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