Why Showers Fail

The short answer: a shower is a stack of layers, each one doing one job. Skip or rush one layer and the ones on top can’t save it. When a shower fails, you usually find out a year later through the ceiling below.

The waterproofing

Grout and tile aren’t waterproof. The membrane under the tile is. Most leaks start where two surfaces meet, not in the middle of a wall: corners, seams, the curb, the niche, the drain connection and pipe holes.

LATICRETE’s HYDRO BAN installation instructions give the numbers: each coat goes on at a wet thickness of 15 to 22 mils, and the membrane has to cure fully before flood testing. More in Waterproofing a Shower.

Watch out: skipping the flood test. Once tile is on, a leak is a tear-out. We plug the drain, fill the pan and leave it overnight before any tile goes down. Best way? Do your research and hire a pro.

Slope and the drain

LATICRETE’s HYDRO BAN instructions call for a minimum slope to drains of 1/4 inch per foot. Too little slope and water sits in puddles, which means soap scum, mould and grout that never dries. A drain set too high or too low forces a bad slope. Because the slope is built into the bed, fixing it usually means redoing the floor. More in Shower Pan Slope and Drains.

The mortar bed

A bed that’s mixed too dry or too wet, or not packed hard, can stay crumbly and weak under the tile. More in LATICRETE 3701 vs Sand Mix.

Watch out: crumbly floor mud. A basic bagged sand mix that’s mixed too dry or too wet can crumble under the tile. We use LATICRETE 3701 Fortified Mortar Bed, mixed right. Best way? Do your research and hire a pro.

Tile, grout and silicone

Dabbing thinset on in dots leaves hollow spots behind the tile, so it cracks and pops loose. Corners and changes of plane get flexible silicone, not grout, because buildings move. More in How to Build a Shower Step by Step.

What we see in the field

“I’ve torn out hundreds of showers in my life, and I’ve seen a lot of bad installs.”

“I’ve seen lots of wood curbs fail, and lots of FOAM pans and FOAM curbs fail.”

Mike Bourdages, Burlington Tile

There are a few ways to do this job. See both side by side in What’s in Your Shower, or peel back every layer in the 3D shower cutaway.

Frequently asked questions

Why does water pool on my shower floor?

Usually the slope is too shallow, uneven, or the drain was set too high. It’s built into the bed, so fixing it usually means redoing the floor.

Is grout waterproof?

No. Grout fills the joints. The membrane underneath is the waterproofing.

Why is my shower floor mortar crumbling?

Usually it was mixed too dry, not packed hard enough, or not cured before the next layer.

A shower is one part of a full bathroom remodel. Here’s how we handle the rest.

By Mike Bourdages, Burlington Tile.