How to Prepare a Surface for Tiling

Before tiling, confirm that the substrate is stable, clean, sufficiently flat and ready according to the materials used. A leaking area, moving screed, powdery plaster or major level change must be dealt with before choosing the adhesive and starting the layout.

1. Check stability

Look for debonded patches, cracks, hollow areas, crumbling edges and a dusty surface. Old paint, weak filler and a loose top layer do not become reliable because tile will cover them. Remove weak material until the remaining substrate is sound.

2. Clean and degrease

• Remove dust, construction debris, oil and loose remnants of earlier coatings.
• Repair holes and cracks with a compatible compound instead of using adhesive to hide a major level change.
• After wet cleaning, allow the surface to dry when the material instructions require it.
• Keep protective film and dirt away from areas that must bond to the adhesive.

3. Check flatness and geometry

Use a long straightedge or another suitable tool to identify high and low areas. Adhesive can only be applied within the range stated for the product, so it should not become the main levelling layer. Mark niches, pipes, corners and other features before fixing the layout.

4. Decide whether primer is needed

Choose primer for the substrate and its absorbency, not simply by label colour. Follow the adhesive system instructions and never use primer as a way to glue a loose layer back to the wall. Wet rooms also need separate checks for waterproofing, junctions, pipe entries and ventilation.

5. Plan before spreading adhesive

• Confirm that the substrate and materials are within the conditions stated by their manufacturers.
• Dry-lay several rows and identify visible cuts and pattern directions.
• Choose adhesive for the substrate, tile format and exposure conditions.
• Estimate tile, adhesive and grout from the layout rather than area alone.

Mistakes that lead to debonding

Dusty or moving surfaces, large level corrections made only with adhesive, tiling over an uncured layer and ignoring the source of moisture are common failures. Adding more adhesive does not correct them.