Why are my wall tiles sliding down the wall?

Tile adhesive holds a wall tile by initial grab long before it has any real strength, and grab is finite. Every extra millimetre of bed, every extra kilo of tile and every non-absorbent surface reduces the margin, and slip is what happens when the margin goes.

What you'll need

• a batten and fixings
• an adhesive rated non-slip or for the tile size and weight
• a scraper for removing failed adhesive
• the adhesive data sheet

Step by step

1. Act while the adhesive is soft.A slipped tile can be lifted, the bed adjusted and the tile re-bedded in the first hour or two. After that the only option is cutting it out.
2. Check the bed thickness.A thick bed of adhesive has more mass and less grab per unit area. If you were using extra adhesive to take up an uneven wall, that is the cause — the wall needs correcting, not burying.
3. Check the tile weight against the adhesive.Adhesives state a maximum tile size or weight for vertical work. Large or heavy tiles on a general-purpose adhesive slip, and no amount of technique changes that.
4. Check the substrate's absorbency.On an absorbent wall the adhesive stiffens quickly as the wall draws water out. On glazed tiles, painted walls or a tanking membrane, nothing draws water out and the adhesive stays mobile far longer, so grab is much lower for much longer.
5. Fit a support batten and build off it.The first row must be carried by something other than adhesive. A batten screwed to the wall takes the weight of every row above it while the whole panel sets.
6. Use a non-slip or high-grab adhesive.Products are formulated for vertical work with additives that resist slump. On large or heavy tiles this is the specific product to look for.
7. Support tiles individually if needed.Wedges, spacers under the bottom edge, or tape across the face to the tile above. Anything that carries the weight until the adhesive has set.
8. Work in smaller areas and let sections set.A full wall of heavy tiles all placed at once is a lot of accumulated weight bearing on the lowest row.
9. Leave everything undisturbed for the set time the data sheet gives.Grouting, removing battens or leaning on a wall too early is how a panel that had held moves anyway.

Tips

• Slump and slip are worse in cold conditions, because cement adhesive stiffens more slowly.
• If the adhesive squeezes up through the joints when you press a tile, the bed is too thick for that tile and notch combination.
• Very smooth non-absorbent substrates such as a tanking membrane are exactly where slip is most likely — read the adhesive's guidance for non-absorbent backgrounds.
• Never tile onto a wall in one continuous session up to a great height with heavy tiles. Let the lower part take a set first.

Common mistakes

• Using adhesive as a levelling material on an uneven wall — The thick bed needed to bury a hollow has far less grab per unit area and far more mass, so those tiles slip while the ones on a thin bed hold. It also cures unevenly and shrinks, so even when it does hold it produces lippage and voids.
• Starting the first row on the floor or the bath — The bottom row is carrying every row above it. If it is resting on an uneven surface, or on nothing at all where the surface falls away, the whole panel creeps downwards as the adhesive settles.
• Using a general-purpose adhesive for heavy or large tiles — The initial grab is simply not designed for that mass on a vertical surface. This is a specification problem, not a technique problem, and the data sheet states the limits.

If it doesn't work

Questions people ask