Cracked or drummy tiles: repair or replace?

A cracked tile or one that rings hollow when you tap it is a common find in older homes. It is easy to assume the whole floor is on its way out, but often the damage is local. The important question is why it happened, because that decides what fixes it.

What "drummy" means

A drummy tile is one that sounds hollow when tapped, a bit like a drum. It means the adhesive underneath has lost contact with the tile, in part or in full. The tile may look fine, and it might stay put for years, but it is more likely to crack under load and it can eventually lift.

You can find drummy tiles by tapping with a coin, the handle of a screwdriver or a small rubber mallet. Move across the floor in a grid and listen for the change in note.

Common causes of cracks and hollow tiles

• Patchy adhesive coverage when the tiles were laid, leaving voids underneath
• Movement in the slab or floor below, including settlement and seasonal shifts
• Missing or inadequate movement joints in larger tiled areas
• Impact from something heavy being dropped
• Moisture reaching the bedding or substrate and weakening the bond
• Heat or sun exposure on tiles that were not designed for it

Reading the pattern

One isolated crack with a clear cause, such as an impact, is usually a single-tile job. A line of cracks running across several tiles, or cracks that follow a straight path across the room, points to movement in the structure and needs more thought. A group of drummy tiles in one area suggests the original fixing was poor in that spot, or that water has been getting in.

When replacing individual tiles makes sense

• The cause is clear and has been dealt with
• The damage is limited to a few tiles
• The surrounding tiles are firmly bonded
• You have spare tiles, or a close enough match is available

Replacing a single tile involves breaking it up carefully, removing the adhesive underneath, fixing a new tile, and regrouting the joints around it. The risk is chipping the neighbours or leaving the new tile slightly out of level.

When a larger repair is better

• Large patches of hollow tiles, which suggests the bond has failed across an area
• Cracks spreading over time rather than staying put
• Tiles lifting at edges or doorways
• Signs of moisture such as staining, odour or efflorescence

In those cases lifting and relaying a section, and sometimes the whole room, is more reliable than patching one tile at a time. The underlying cause also needs sorting out, otherwise the new tiles will crack in the same way.

What about injecting adhesive?

Some drummy tiles can be re-bonded by drilling a small hole and injecting adhesive or resin underneath. It can work for a lone hollow tile that is otherwise intact, and it avoids the cost of replacing it. It is less suitable where the tile is also cracked, where moisture is involved or where a large area is affected.

DIY or professional?

Swapping one wall tile or a floor tile in a low-stress area is within reach for a careful DIYer. The harder part is matching tile, level and grout. For floors with several affected tiles, anywhere with a waterproof membrane underneath, or anything that looks like structural movement, an assessment by a tiler is worth the time. A short inspection will tell you whether you are looking at a patch or a larger job.