Surface preparation before tiling
Getting the foundation right before the first tile goes down
Why preparation matters more than the tiles
The most expensive tiles will crack or pop off a poorly prepared surface. Tile failures are almost never about the tile — they are about what is underneath. Proper surface preparation is the single most important step.
The universal rules
Every substrate must be flat (within 3 mm over 2 metres), clean, dry, and stable. For large-format tiles over 60 cm, flatness tolerance drops to 1.5 mm.
Key steps
- Check flatness with a 2 m straightedge. Mark high spots and hollows.
- Grind down high spots. Fill hollows with patching compound.
- Clean thoroughly. Vacuum, do not just sweep. Remove dust, grease, old adhesive.
- Apply primer. Controls moisture absorption, improves adhesive grip. Use the primer your adhesive manufacturer recommends.
- Level if needed. Self-levelling compound for floors. Skim coat for walls.
- Waterproof wet areas before tiling. See waterproofing guide.
Common substrates
- Concrete screed: Must cure 28 days minimum. Prime to control suction.
- Plasterboard: Use flexible rapid-set adhesive. Use plasterboard-specific primer (not water-based).
- Plywood: Must be exterior-grade (WBP). Prime with SBR, add decoupling membrane. Never tile on chipboard.
- Existing tiles: Sand surface, degrease, use bonding primer. Tap-test for hollow tiles first.
Tip: The most common DIY mistake is tiling onto dusty or unprimed surfaces. The adhesive bonds to the dust, not the substrate. Five minutes of priming prevents years of problems.
Plan your tile layout on a properly prepared surface
Open Tile Cut Plan →