What’s Behind Your Shower Tile?
Tile and grout aren’t waterproof. Learn why showers need a waterproof layer, the signs of a hidden leak, and how The Great House fixes it.
BATHROOM REMODELING
12/5/20263 min read
ASK MASON · BATHROOM
What’s Behind Your Shower Tile? Why Grout Isn’t Waterproof
Mason shows what really keeps your shower walls dry, the warning signs, and how we rebuild it.
Your tile shower might be leaking right now, and you’d never know.
Watch Mason’s video, then read what keeps a shower dry, the signs of a hidden leak, and how we fix it.
IN THIS GUIDE
01
What Mason Checks
The Layer That Keeps Your Shower Dry
TILE AND GROUT
Look solid, but grout soaks up water.
WATERPROOF LAYER
Behind the tile, it catches every drop.
TO THE DRAIN
The layer sends water down into the drain.
Tile and grout look solid, but they’re not waterproof. Grout is like a hard sponge: water soaks right through it.
That’s why a good shower has a waterproof layer behind the tile. It catches every drop and sends it down to the drain.
Many showers were built without one, or the layer was torn, or never sealed at the corners.
Mason’s diagram: water passing through grout to the wall behind the tile
The tile is the finish. The waterproofing is the shower.
02
Warning Signs
Signs of a Hidden Shower Leak
HOLLOW TILES
Loose or hollow-sounding tiles.
DARK GROUT
Grout that stays dark long after a shower.
CEILING STAIN
A stain on the ceiling below the bathroom.
Water passes through the grout and soaks the board and the wood studs behind the wall.
Month after month, the wood stays wet. It grows mold, starts to rot, and the water can spread into the floor and the ceiling below.
Check this today
Tap the tiles with a coin: a hollow sound means the tile has lost its bond. Check the ceiling below the shower for stains.
03
How We Fix It
A Small Repair Now, or a New Shower Later
We remove the tile and open the wall. We replace any wet or rotted wood, install new cement board, and add a continuous waterproof membrane, sealed at every seam and corner, before new tile goes on.
Caught early vs. caught late
Caught early, it’s a small repair. Caught late, it’s a whole new shower.
In Northern Virginia
Many Northern Virginia homes are 40 to 60 years old. In Arlington, about 45% of homes were built before 1970 (U.S. Census, 2019–2023). Many showers from those years were built before modern waterproof membranes were common. We rebuilt a shower like this on our Inwood Dr renovation in Springfield.
Planning a bigger project?
Remodeling your bathroom? Every shower we build gets a continuous waterproof membrane before the tile. See prices and real projects on our bathroom remodeling page.
The fix: new cement board behind the shower wall
ASK MASON · BATHROOM
Want to know another problem?
SPOTTED ONE OF THESE SIGNS?
We’ll check it before it turns into a big repair
Free in-home visit from a Class A licensed team. We check the problem and the rest of your bathroom, then give you a clear written plan.
ABOUT THE AUTHOR
The Great House team
Written by the team at The Great House LLC, a Class A licensed builder and remodeler in McLean, VA (License #2705197237). We have renovated 30+ Northern Virginia homes since 2022.
PLANNING A PROJECT?
Our bathroom remodeling service
See prices, real photos and how we work: our bathroom remodeling page. Real projects: our project gallery.
Serving McLean, Vienna, Great Falls, Fairfax, all of Northern Virginia.