Prepare walls for tiling
Save £150–400 — this is the step most people skip
Most tiling failures come back to poor prep. Tiles crack, pop, or drift out of line — not because of bad tiling, but because the wall behind them was not ready. This guide fixes that before it becomes a problem.
Last updated: June 2025
Only basic tools needed — most homes already have them.
Before you start
Walls must be clean, stable, and structurally sound before tiling. This guide covers surface prep only — it does not cover replastering, fixing structural damage, or treating active damp.
Bathrooms need moisture-resistant preparation. Use tile primer or moisture-resistant PVA — not standard decorating PVA.
If you find crumbling plaster, significant damp, or walls that flex when pressed, stop and fix those issues first. Tiling over them will not hold.
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Tools & materials
- ✓Filling knife / scraper— for removing old adhesive and applying filler
- ✓Sandpaper (mixed grit)— 80-grit and 120-grit for filling and blending
- ✓Spirit level— check flatness and plumb before setting out tiles
- !Wall filler— use a ready-mixed or powder filler rated for bathrooms
- !Tile primer or PVA— moisture-resistant — not standard decorating PVA
Want everything in one go?
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Remove old adhesive and debris
Use a scraper or filling knife held at a low angle to work off any lumps of old tile adhesive, render blobs, or wallpaper paste. Work across the whole surface — not just where the old tiles were. For stubborn spots, score with a Stanley knife first to break the bond. Why: adhesive tiles onto lumps and you get lippage — where tile edges sit at different heights. Even a 2mm lump behind a tile will show as a visible ridge at the grout line. Start with a flat wall and the rest of the job becomes straightforward.
Most people get this done in under 5 minutes.
Quick guides for this phase
How to check if a wall is level and flat before tiling →Where beginners go wrong
Skipping prep entirely. “The wall looks fine” is not good enough. Old adhesive, paint, or dust all reduce the grip area for new tile adhesive. Run your hand across the wall — if it comes away chalky or gritty, the surface needs priming first.
Tiling onto dusty or powdery surfaces. Sanding and scraping produces fine dust that settles back onto the wall. Always wipe down with a damp cloth and allow to dry before applying primer. Tile adhesive sticks to the wall, not to a layer of dust sitting on the wall.
Ignoring uneven walls and hoping adhesive will compensate. Tile adhesive can absorb 2–3mm of variation at most. Beyond that, tiles will rock, crack, or have hollow spots behind them. If the wall deviates more than 3mm, address it at the prep stage — not during tiling.
Stop and call a professional if...
The plaster crumbles or breaks away when pressed — the wall needs replastering before any tiling work
You find active damp — dark spreading patches, moisture beading, or a persistent damp smell — this needs a damp specialist before any surface treatment
The wall surface deviates more than 10mm over 1.8m — this level of unevenness requires a render or skim coat, not extra adhesive
Cost breakdown
Recommended starter kit
Five tools that cover most home repairs.
- →Adjustable spannerAmazon·Screwfix
- →Screwdriver setAmazon·Screwfix
- →PTFE tapeAmazon·Screwfix
- →Spirit levelAmazon·Screwfix
- →Tape measureAmazon·Screwfix
Want everything in one go? Get it on Amazon
What you just learned
You now understand how to assess a wall surface before tiling — not just look at it, but press it, probe it, and measure it. You can fill and sand to a flat finish, and you know why priming matters before adhesive goes on.
These are the foundation skills that separate a tiling job that lasts 20 years from one that starts popping tiles at year two. The wall you have prepared is now genuinely ready.
This unlocks:
Continue your renovation
Most people skip this step and wonder why their tiles fail.
⚠️ Watch out if you rent
Wall prep for tiling is a permanent change. Always get written permission from your landlord before tiling in a rented property. The prep work itself (filling, sanding, priming) is fine — but it implies tiling is coming, which requires explicit agreement.