Updated
Tiles That Sound Hollow When Tapped
Some tiles give a drummy, hollow note when tapped, and you want to know whether they are about to fail.
Find a tiler
What's happening?
A hollow note means a void. Where a tile is fully bedded, the tap is transmitted into the adhesive and the background and comes back dull and solid; where there is air behind it, the tile rings. Drumminess is therefore a coverage report, not a bond test — it tells you how much of the tile is actually supported, which is what decides whether it cracks under load. The usual cause is spot fixing: five dabs of adhesive under each tile leaves most of the back unsupported, and the tile then behaves like a small unsupported slab. Position matters more than area. A void in the middle of a wall tile is often harmless for years, while a void under the corner or edge of a floor tile in a doorway is a crack waiting for the right footstep.
What usually causes it?
- Tiles fixed on dabs, spots or ribbons of adhesive rather than a full, combed bed
- Adhesive that had skinned over before the tile was placed, so it never wet out the back of the tile
- Tiles not back-buttered where the format, the keying or a heavily ribbed back needed it
- An uneven or hollow background that the adhesive bed was expected to bridge instead of being dubbed out first
- A dusty, friable or unprimed background, so the adhesive gripped the dust rather than the substrate
- Movement in the background after fixing, breaking the bond over part of the tile
- Water reaching the bed through open grout or a failed sealant line, softening the adhesive and releasing it
Is it dangerous?
Hollow tiles are a medium risk that depends almost entirely on where they are. On a floor, unsupported tiles crack under point loads and the broken edges are sharp and become a trip; in a doorway or on a stair nosing that is worth acting on rather than monitoring. On a wall, a drummy tile stays put until something disturbs it, and the risk is that it eventually drops — which matters over a bath, a hob or a basin, and matters more if the tiles are large-format and heavy. The second-hand risk is water: once a hollow area cracks or a joint opens, the void behind it fills and stays wet, and you cannot see it happening.
Can I fix it myself?
Surveying it is genuinely useful and completely safe. Tap methodically with a knuckle, a coin or the handle of a screwdriver, and mark every drummy tile with low-tack tape so the pattern shows — voids that follow a straight line usually mean the background, while scattered single tiles usually mean the fixing. Note whether they are on a route people walk or somewhere a falling tile would matter. Replacing an isolated hollow tile is reasonable DIY if you have spares. What does not work is injecting adhesive through the grout joints or trying to squeeze filler behind a tile: the void does not fill, and the tile is no better supported than it was.
When should you call a tiler?
Call a tiler where hollow tiles are widespread, where they sit on a floor route or above a bath, hob or basin, or where drummy tiles have already started cracking. Where a whole area sounds hollow the honest answer is usually relaying that area rather than picking off individuals, and it is worth knowing that before you buy replacement tiles. Call sooner if a hollow tile is also loose, moves under foot, or has an open grout joint letting water in.
What will the tiler actually do?
- Tap out and map the drummy area, so the extent and the pattern are known before anything is lifted
- Lift a tile to measure the actual adhesive coverage and see whether the failure is fixing or background
- Prepare the background properly — dubbing out hollows, removing dust and friable material, priming as required
- Refix on a full combed bed, back-buttering where the tile format or the tile back needs it
- Relay whole areas where coverage is poor throughout, rather than replacing single tiles into a failing field
- Regrout and reseal the affected area, keeping flexible sealant in the corners and perimeter joints
Frequently asked questions
We’re happy to answer all your questions.
Sources & References
Need a tiler?
Compare local tilers on Tradehand — coverage areas, accreditations and phone numbers, no middleman.