A tiled shower can look perfect on day one and still leak. The tile and grout are not what keeps water out. The waterproof layer underneath does that job, and once tile goes on, that layer is out of sight for good.
That is why we flood-test our shower pans.
What a flood test is
The drain is plugged and the shower floor is filled with water, so the pan floor and the lower part of its turned-up edges sit under standing water. Then the water level is watched, along with the space below and around the shower. If the level drops or moisture shows up where it shouldn’t, the pan has a leak, and it gets found while it is still cheap to reach.
Some builders add a few drops of dye to the water. A slow seep is hard to see when the water is clear; colored water shows up faster on the subfloor or on a ceiling below.
Where leaks show up most often
Most shower leaks start at a joint or an opening, not in the middle of a flat surface. These are the places leaks show up most often:
- The curb, especially its two ends where it meets the walls
- Low walls and knee walls next to the shower
- A built-in bench or seat
- Inside corners, where two walls or a wall and the floor meet
- The niche
- The valve hole behind the shower handle
- Around the drain
If you want to see how those layers go together, we walked through a walk-in shower layer by layer here: What’s Behind Shower Tile? A Walk-In Shower, Layer by Layer.
If you are planning a new shower
Ask your contractor three things:
- What is the waterproof layer under the tile, and does it turn up the walls and over the curb?
- Will the pan be flood-tested before tile goes on?
- How are the niche, the bench and the valve hole sealed?
A clear answer to those three tells you more than any tile sample.
Sun Shore Construction is a licensed remodeling contractor serving Greater Boston.
More from our bathroom work: bathroom remodeling, how we work, and recent projects.
