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What does it mean when tiles sound hollow?

The short answer

A hollow or drummy sound means the tile has lost its bond to the substrate. It is not always urgent, but in a wet area it is a path for water and it tends to spread.

TradieAnswers editorial · written in-house and sourced to the authorities listed below

Checked against 4 published sources, listed in full at the end of this page. How we source this

Tapping a well-bonded tile gives a solid, dull sound. A tile with a void beneath it rings hollow. That void means the adhesive has either failed or was never in full contact, and the tile is being held by its edges and its grout.

Why it happens

  • Insufficient adhesive coverage, particularly spot bedding rather than a full bed, which is a common shortcut.
  • Movement in the substrate, including slab shrinkage and seasonal timber movement.
  • No movement joints in a large tiled area, so expansion has nowhere to go and the bond breaks instead.
  • Tiling onto a substrate that was damp, dusty or not primed.
  • Water getting under the tiles and breaking the bond from below, which is the wet area case.

When it matters

  • In a shower or wet area, it matters, because the void holds water against the membrane and the problem spreads.
  • On a floor, it matters if the tile is likely to crack under load or become a trip hazard.
  • On a large area of an external deck or balcony, it usually indicates a movement or waterproofing problem worth investigating.
  • One or two drummy tiles on an otherwise sound internal wall is often tolerable and worth monitoring.

Who does this work

You may need a tiler

Because loose tiles on their own are a tiling job, but if the substrate is moving or a wet-area membrane has failed it becomes building work.

Depending on the cause it can also involve builder or waterproofer.

This is not a licensed trade in itself, though nearby work may be. Check a licence in your state

Sources

Every source below was fetched and its response recorded on the date shown. Where a government site blocks automated clients, that is noted rather than reported as a successful check.

  1. Standards Australia · Standards AustraliaChecked 2026-08-10 · responded 200 OK
  2. National Construction Code · Australian Building Codes BoardChecked 2026-08-10 · responded 200 OK
  3. Guidance material and handbooks · Australian Building Codes BoardChecked 2026-08-11 · responded 200 OK
  4. Home warranty insurance obligations · Queensland Building and Construction CommissionChecked 2026-08-10 · responded 200 OK

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