Why Tile Showers Leak (and How Proper Waterproofing Prevents It)

Most people assume tile and grout keep water out of their walls. They don't. A tile shower stays dry because of what is underneath the tile, and when that part is skipped or done wrong, the shower can leak for years before anyone notices.

Tile and grout are not waterproof

Porcelain tile itself sheds water well, but grout is porous. Water soaks into grout lines every time you shower, and some of it works its way through to whatever is behind the tile. Sealer slows this down, but it does not stop it, and it wears off over time.

That is normal and expected. A properly built shower is designed for it: behind the tile there is a waterproof layer that catches the water and sends it to the drain. The tile is the finish. The waterproofing is the structure.

The most common reasons tile showers leak

• No real waterproofing layer. Older showers, and some newer ones, were built with tile over plain drywall or a moisture barrier that was never continuous.
• Gaps at seams, corners and niches. A membrane is only as good as its weakest seam. Corners, niche edges, the curb and the joint where wall meets floor are where most failures start.
• Bad slope on the floor. If the floor does not slope evenly to the drain, water sits in low spots and keeps soaking the grout.
• A poorly connected drain. The waterproofing has to tie into the drain properly, or water that reaches the membrane has nowhere to go.
• Penetrations that were never sealed. The valve, shower head arm and any other holes through the wall need to be sealed into the waterproofing.
• Cracked or missing caulk at changes of plane. Corners and the joint where the wall meets the floor or tub need flexible caulk, not grout, because those joints move.

Warning signs your shower is leaking

• Grout that stays dark long after a shower
• Loose or hollow-sounding tiles
• Peeling paint, bubbling or soft drywall on the other side of the wall
• Stains or a musty smell in the room below
• Mold that keeps coming back in the same corner
• Cracked grout along the bottom row or in the corners

If you see more than one of these, it is worth having the shower looked at sooner rather than later. Water damage behind tile tends to spread quietly into framing and subfloor.

What proper waterproofing looks like

A well-built tile shower has a continuous waterproof layer on the walls, the floor, the curb and inside every niche, with no gaps. That layer is usually a sheet membrane or a liquid-applied membrane, installed to the manufacturer's instructions, with seams overlapped and corners reinforced.

• The floor is sloped to the drain before the waterproofing goes on, so water drains instead of pooling
• The membrane ties into the drain assembly
• Niches and benches are waterproofed inside and out, not just tiled
• Every pipe penetration is sealed
• Corners and changes of plane get flexible caulk, not grout

Many installers also flood test the shower floor before tiling, filling it with water and checking for leaks while fixing a problem is still easy.

Can a leaking shower be fixed without tearing it out?

Sometimes. If the problem is failed caulk at the corners or worn-out grout, regrouting and recaulking can solve it. If the leak comes from missing or failed waterproofing behind the tile, the honest answer is usually that the shower needs to come out and be rebuilt properly, because there is no way to add a membrane behind tile that is already installed.

The good news is that a rebuilt shower is a chance to get the layout, niches and tile you actually want, built to last.

Ready to talk about your project? Learn more about our custom showers services, or call (706) 671-5786 for a free in-home estimate. Palacios Installation is based in Chatsworth, GA and works in homes across Chattanooga, Hixson, Signal Mountain, Lookout Mountain, Dalton and North Georgia.