From the Blog · Bathrooms
Why does my shower grout stay wet — and when is it a leak?
Straight answer: grout that is still dark and damp two or three hours after a shower is holding water it should have shed. The three usual causes are a shower floor built without enough fall (it needs a quarter inch per foot toward the drain), cracked grout or silicone in the corners letting water behind the tile, and waterproofing that was never there in the first place. Occasionally it is just a cold room and no extractor fan — but grout that never fully dries between showers is a leak until proven otherwise.
First, rule out the innocent explanation
Steam and a cold room. In a Colorado winter the walls are cold, the steam condenses, and everything stays damp longer — especially with no extractor fan, or a fan switched off the second you step out. Run the fan 20–30 minutes after your shower for a week. If the grout dries properly between showers after that, you had a ventilation problem, not a building problem. Cheap fix, job done.
The three causes that are not innocent
1. A flat pan. A shower floor must fall a quarter inch per foot toward the drain, built into the mud bed before tiling. A flat — or worse, back-falling — pan leaves a permanent puddle under and between the tiles. The grout over it never dries, goes dark, then black at the edges. No amount of sealing fixes geometry.
2. Cracked corners. Corners move. Grout in a corner cracks, and every shower pushes water through the crack behind the tile, where it soaks the wall board. Corners should be silicone, not grout, precisely because silicone flexes. Dark grout plus a cracked corner line is water going where it shouldn't, every single day.
3. No waterproofing behind the tile. Tile and grout are not waterproofing — they are a finish. The waterproof layer is the membrane behind them. In plenty of older Colorado Springs showers there simply isn't one, so the wall drinks a little of every shower and the grout stays wet because the wall behind it is wet.
When it becomes urgent
Soft or spongy wall at the base of the shower, a musty smell that cleaning never shifts, grout that crumbles, or water showing in the room below — that is no longer a maintenance question. Water behind tile does its damage quietly and bills you later, with interest. Caught early, the fix can be as small as raking out and re-siliconing the corners; caught late, it is a rebuild of the wet area.
The short version
Grout should dry between showers. If yours doesn't, check the fan first, then the corners, then suspect the pan and the waterproofing — in that order. And if you're in Colorado Springs, Monument, Falcon or anywhere along the Front Range and want a straight answer, text a photo to The British Remodeler at 719-521-8312.
Grout that never dries?
Text a photo to 719-521-8312 and get a straight answer about what it is — and what it isn't.