Water Behind the Tile:
How Tub Surrounds, Shower Walls and Shower Pans Fail
Tile and grout keep most of the water out. The layer behind them handles the rest, and nobody sees it until it’s failed.
In one Portland hallway bathroom, the shower tile was failing and there were signs the shower had leaked. The report said what that combination usually means: there’s likely damage behind the tile that can’t be seen from the bathroom.
That’s the trouble with tiled showers. Cracked grout and a chipped tile look like small cosmetic things, and sometimes they are. Other times they’re the visible end of a wall that has been taking on water for years. In 88 of Russ’s 269 recent inspection reports, a shower or tub had a tile, grout, surround or pan finding.
What keeps the water out of the wall
A tiled shower is a stack of layers. Tile on the surface. Grout between the tiles. Behind them, a backer board, and either a waterproof membrane or a moisture barrier. The tile and grout take most of the spray. The backer and membrane are what keep the wall framing dry.
Grout isn’t waterproof. Cement grout and many tiles absorb some water every time the shower runs and dry out between uses. That’s normal, as long as the layer behind them is doing its job and the grout is intact enough to keep the volume down.
Older bathrooms and quick remodels are where the hidden layer gets shortcut. Current residential code calls for cement board, fiber-cement or glass-mat backers behind tile in tub and shower areas. Regular drywall and old green “water-resistant” board behind shower tile still turn up, and both soften when they get wet. In one Portland bathroom, the tile around the tub stopped partway up the wall and left painted drywall in the splash zone.
Cracked grout, loose tile and poor tile work
Cracked or missing grout came up in more of Russ’s shower findings than anything else. Some of it was wear. Some of it was installation. A Vancouver primary shower had large areas where the grout was missing entirely. Showers in Gresham, Canby and Clackamas had tile work the reports described as poor or DIY quality, with uneven spacing and poorly filled grout lines.
Patterns in the cracking say more than a single crack does. Grout that cracks along the bottom course, or keeps cracking in the same line after it’s been redone, points to movement or water behind it. In one Portland shower, the bottom row of tiles had been replaced at some point and the grout above it had cracked again. A Troutdale shower had cracks running both vertically and horizontally through the tile, which usually means the wall behind it is moving.
Mold-like growth in grout is common and often a cleaning and ventilation issue. It turned up in Gresham, West Linn and Brush Prairie. When it shows up with cracked grout, it means water is sitting in those joints long enough to grow something. The post on bathroom fans covers the ventilation side.
The joints that should flex
Some joints in a bathroom are supposed to move: where the tub meets the floor tile, where the tub meets the wall tile, and the inside corners of a shower. Tile industry guidance calls for a flexible sealant at those changes of plane, not grout.
Rigid grout there cracks as the tub settles under water weight and the floor moves with the seasons. Russ found cracked tub-to-floor joints in 18 houses. Water that gets into that crack runs straight down to the subfloor. One Sandy report found the opposite problem: a heavy, thick bead of sealant at the base of the shower that had cracked and pulled away, which often means it was laid over an older failing joint.
The post on tub and shower caulk covers that joint along with apparent mold on caulk and swollen baseboards next to the tub.
Shower pans and surrounds
A one-piece acrylic or fiberglass pan has its own ways of failing. Russ wrote up pan damage in about 40 houses: cracks, chips through the finish, gouges near the drain, and blistering. A La Center pan flexed underfoot with audible cracking and popping, a sign it isn’t fully supported. An Aloha pan had damage covered with duct tape. A Canby pan in a newer house had a crack with a surface repair over it. A Portland pan had been refinished, and the coating was bubbling.
Surrounds give warnings too. In a Gresham bathroom, the tub surround bulged inward behind the spout and handle, which often means water has been getting into the wall at the valve. In Camas, a tub had a creased, cracked corner.
Tiled shower floors built on a mortar bed are harder to judge. The waterproof liner sits under the mortar and tile, so the only clues are what shows up around and below the shower: a stain on the ceiling under it, a wet reading on the subfloor in the crawlspace, or loose tile at the curb.
Real Inspection Photos
Shower Tile and Pan Findings From Russ's Inspections
Grout, tile and surround problems Russ has written up in Portland-area showers and tubs.
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Large areas of grout were missing in this primary shower. The report recommended a tile contractor regrout and reseal it. -
The bottom course of tile in this shower looked previously replaced, and the grout above it had cracked again. -
Cracks running both vertically and horizontally through shower wall tile, which usually points to movement behind the wall. -
The tub surround bulged inward behind the spout and handle, a pattern that often means water has been getting into the wall at the valve. -
Failing tile in a hallway shower that also showed signs of leaks. The report noted hidden damage behind the tile was likely.
What a home inspection can and can’t see
Russ runs the shower and the tub, checks that they drain, and looks at the tile, grout, caulk, pan and surround. He uses a moisture meter and the thermal camera around the shower, and below it when there’s a ceiling or crawlspace to check. The post on what moisture meter readings in a report mean explains why a dry reading on one day isn’t the whole story.
He doesn’t remove tile, open the wall or flood-test a pan. So the report says what’s visible: cracked grout, a soft wall, a flexing pan, a wet reading. When the clues point behind the tile, the next step is a licensed plumber or tile contractor, who can flood-test a pan or open a small area to look. If there’s a stained ceiling under the bathroom, the ceiling stain post covers how that gets read.
- Press on the tile and the wall around the shower; note anything loose, hollow or soft
- Look at the bottom row of tile and the inside corners for cracked or missing grout
- Look for grout at the tub-to-floor joint instead of flexible caulk
- Stand in the shower pan and feel for flexing or listen for popping
- Look at the wall outside the shower and the ceiling below it for stains or peeling paint
- Ask the sellers when the shower was last regrouted or rebuilt, and by whom
Grout and tile shed most of the water; the board and membrane behind them keep the wall dry. Cracked grout, soft walls, flexing pans and grout at joints that should be caulked are the visible clues. A home inspection reports those clues, and a plumber or tile contractor looks behind the tile.
Fresh tile in an older house is worth a second look, and the post on buying a flipped house covers what fresh remodel work can hide. The guide to what to look at in the bathrooms before you make an offer covers the rest of the room. To set up an inspection, you can book online.
Shower Tile and Pan FAQ
