Shower Leaking Behind the Tile? Repair or Rebuild

Signs water is getting behind the tile

A shower can leak for months before it shows. These are the usual signs:

• Grout that's cracked, crumbling or missing
• Gaps in the caulk at the corners or where the tile meets the tub
• Tiles that sound hollow when you tap them, or move when you press
• A soft or spongy spot in the wall
• Stains, peeling paint or a swollen baseboard on the other side of the wall
• A musty smell that doesn't go away after cleaning

Finding where the water comes from

There are four usual sources, and the fix depends on which one it is:

1. The grout and caulk on the surface.
2. The waterproofing behind the tile, which failed or was never there.
3. The shower floor, or pan, under the tile.
4. The plumbing: the valve, the pipe behind the showerhead, or the drain.

The way to narrow it down is to get one part wet at a time. Run water only at the drain. Then wet only the walls. Then run the valve with the showerhead off and watch the pipe. Whichever test brings the leak back points to the source.

Why older Phoenix showers fail

Grout isn't waterproof. It only slows water down. What keeps a wall dry is the waterproof layer behind the tile. In many older homes, shower tile was set over drywall or water-resistant "greenboard," with no real waterproofing behind it. Once water soaks through the grout, that board turns soft and stays wet.

Building codes no longer allow that. Chandler's homeowner permit manual, for example, calls for a tile backer board at showers and says no greenboard.

When a repair is enough

If the wall is firm and the leak comes from the surface, the shower can stay. Worn grout gets ground out and replaced. Old caulk gets cut out, and fresh silicone goes into the corners and the joint where tile meets the tub. A leak at the valve or behind the showerhead is usually a worn cartridge or a loose fitting, fixed from the front without tearing out tile. These are tile and grout and plumbing repairs.

When it has to be rebuilt

If the wall is soft, the tile and the board behind it have to come off. Then the framing gets checked and dried, and any rotted wood gets replaced. A new backer board and a waterproofing membrane go on before new tile. If the floor was leaking too, a new shower pan goes in.

It isn't a weekend job. The waterproofing alone takes a few days to cure before the tile goes on.

If we open the wall and find damage nobody could see beforehand, we stop, show you, and re-estimate before doing more.

While the shower is open

Once a shower is down to the studs, it's the easiest time to make changes. You can move the valve to a better height, add a niche for bottles, or add blocking for grab bars. You can also make the shower bigger, or turn a tub into a walk-in shower. Changes that move the drain take longer, because the drain sits in the slab.

Problems we fix on this page

• Wall behind the shower is soft
• Shower leaking into the room next to it
• Shower leaking to the ceiling below
• Shower pan leaking
• Mold behind the shower tile
• Tile moves when pressed
• Floor soft near the toilet
• Floor soft near the tub

How it starts

Send a photo of the shower and one of the other side of the wall, or ask us to come look. If it's a surface fix, it's a repair visit. If the shower needs rebuilding, you get a written estimate before anything comes apart.