Shower Waterproofing: The Layer Behind the Tile
What goes on behind your shower walls before any tile, the order it goes on in, and what happens to a house when that layer fails.
Behind the Finish
The waterproofing layer under the finish
Shower waterproofing is the membrane, the pan and the drain under the tile or panels, the layer that keeps water out of the walls and the floor.
The finish is only part of what makes a bathroom last. Waterproofing, drainage, ventilation and the "rough-in", the pipes in the wall, protect what sits underneath it, and you never see any of them once the shower is done.
That is why a well-built shower starts with proper waterproofing and a prepared substrate, along with plumbing and a valve installed by trained hands, before anyone talks about tile.
On the surface
Look right, clean easily and take the daily wear. Grout lines and the edges around the valve still let water through over time.
Underneath
Catch every drop that gets past the finish and send it down the drain before it ever touches wood. This is the part that decides how long the room lasts.
Wall to Drain
Membrane, pan and wall board
The walls are prepared with cement board, a waterproofing membrane goes over it, and a sloped pan carries the water to the drain.
These are the layers, from the studs out:
- Cement board
The "cement board", or backer board, fastened to the studs. Walls are prepared with drywall or cement board, and in the wet area it is the water-resistant panel tile is set on.
- Waterproofing membrane
The "waterproofing membrane" is rolled or sheeted over the board in the wet area before any tile or pan finish is set, so the water that gets through the grout stops here.
- Shower pan
The "shower pan" is the sloped, waterproof base under the shower floor, pitched so water only runs one way.
- Drain
Where the slope ends. The membrane ties into the drain body, so what it catches leaves through the pipe instead of around it.
- Tile or panels
The finish, set last over everything else. It takes the wear and gives the look; the layers under it keep the wall dry.
Build Order
Waterproofing before tile
Waterproofing goes on after the rough plumbing is in and inspected, and before a single tile or the pan's finish is set.
Get the order wrong and the membrane is either cut open by a late pipe or covered before anyone has checked what sits behind it.
This is the order a bathroom goes together in:
- Demolition
- Rough plumbing and electrical
- Inspection
- WaterproofingThis page
- Tile
- Fixtures
- Finish work
Before it
The old shower comes out and the new supply lines, drain and valve go into the open wall. Where the work carries a permit, the local building department inspects it while the walls are still open; those departments are certified by the Ohio Board of Building Standards.
The layer itself
Cement board goes up, the membrane goes over it and laps into the pan, and the pan is sloped to the drain. Nothing gets covered until this layer is complete.
After it
Tile or panels go over the membrane, then the fixtures and trim, then the finish work. From here on, the waterproofing is out of sight for the life of the shower.
When It Fails
Water damage behind the shower
When the waterproofing fails, water gets past the tile and reaches the subfloor and the framing, and the damage keeps spreading until it is opened up and repaired.
From the bathroom side the tile can look fine while it happens, because the finish was never what kept the water out. It is also why moisture, framing or subfloor repairs found after demolition add to the cost. When we find them, we show you, write the repair down and wait for your approval before it goes ahead.
When the fix means a new shower, we rebuild it from the pan up:
Before You Hire
Tight work in a small space
Bathroom work packs waterproofing, plumbing, ventilation and tight finish tolerances into one small room.
The membrane has to lap the pan, the valve and shower head pipes pass through the board, the exhaust fan has to clear the steam, and the tile has to land straight at the end. Each layer is hidden by the next, so every one has to be right before it is covered.
Free Estimates
Have Us Look at Your Shower
Call, tell us what the shower needs, and we come out, measure and quote the whole job in writing before any work starts.
Monday through Saturday. Calls outside those hours go to voicemail and we return them the next working morning.
- The whole job quoted before we start
- We show up when we say we will
- We clean up when the work is done