Blog · 6 min read
The 7 Tile Mistakes That Show Up a Year Later
Skips that pass inspection on day one and fail by month twelve: no membrane, thin coverage, slivers at the doorway, wrong caulk, and more.
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1. Tile as waterproofing
Grout and tile are not a waterproofing system. Showers built tile-over-drywall or tile-over-bare-cement-board look perfect on day one and grow mushrooms by year two. The membrane behind the tile is the shower; everything else is decoration.
2. Thin mortar coverage
Spot-bonding (five blobs of mortar per tile) leaves the tile mostly unsupported. It holds until something heavy drops, then the hollow corner shatters. Floors need 80% coverage minimum, wet areas 95%. Pull up a tile early and look.
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3. Slivers at the doorway
A 1-inch tile sliver at the room's most visible threshold is a layout failure, not bad luck. Dry-lay from the focal point toward the walls before mixing mortar; shift the centerline so cuts at both ends are at least half a tile.
4–7. The supporting cast
Four more that pass the eye test and fail the calendar:
- 4. Grout in change-of-plane joints — corners and counters move; use color-matched caulk or it cracks
- 5. No movement joints — floors need perimeter gaps and, on big rooms, soft joints every 20–25 ft
- 6. Tiling over a bouncy floor — cracked grout lines trace every joist within a year
- 7. Wrong thinset for the tile — unmodified under porcelain or modified where a membrane forbids it
Do this math on the job site — in the free app
Smart Tile Calculator for Android: offline, in your pocket, free.
FAQ
What's the single most common tile failure?
Water damage from missing or incomplete waterproofing in showers — it's the most expensive and the most hidden, often appearing as damage in the room below, not in the shower itself.
Why did my grout crack in the corners?
Corners are change-of-plane joints that move with seasons and structure. Grout is rigid and cracks there by design — those joints should be flexible color-matched caulk.
Can these be fixed without a full tear-out?
Caulk and grout issues, yes — rake out and redo. Coverage, membrane and substrate problems, no — they require removing tile, which is why the cheap quote is expensive.
Keep reading
- Waterproofing a Tiled Shower: The Layer Cake That Keeps Water Out
Why tile and grout are not waterproof, how sheet and liquid membranes work, where corners and niches fail, and the flood test you shouldn't skip.
- Can You Tile Over Existing Tile? When It Works and When It Fails
The bond test that decides it, height and door-clearance math, prepping glossy tile for mortar, and the situations where removal is the only honest answer.