Tile on Tile: Re-Tiling Without Breaking the Old Floor

Breaking an old floor is noisy, dusty and slow, and in a lived-in home it can mean days of debris carried through the house. That is why so many people ask whether they can fit tile on tile, laying new tiles straight over the old floor. The short answer is yes, in many cases it works very well. The longer answer is that it only works when the old floor is checked properly and the right adhesive is used.

We have done tile-on-tile work in flats, bungalows and shops where demolition was not practical. We have also been called to repair tile-on-tile jobs that failed because the old floor was hollow underneath. This guide covers how to tell the difference.

When tile on tile makes sense

• The existing tiles or stone are firmly bonded, with very few hollow spots.
• The floor is reasonably level and has no major cracks.
• You can accept the floor rising by the thickness of the new tile plus adhesive.
• There are no hidden leaks or damp under the old floor.
• Doors, kitchen platforms and fixtures can be adjusted for the new height.

When you should break the old floor

• Many tiles sound hollow when tapped, or some are already loose.
• There is dampness, efflorescence or a plumbing leak under the floor.
• The floor is badly out of level or has cracks that run through tiles and screed.
• The height increase would create a step at a doorway or make the bathroom floor higher than the shower drain allows.
• The old floor is soft ceramic that is cracking under load.

Testing the old floor

The tap test

We tap every tile with a small hammer or the handle of a tool. A solid tile gives a sharp, firm sound. A hollow tile sounds dull and drummy. Mark every hollow tile with chalk. A few scattered hollow tiles can be removed and the gaps filled with a cement-based patch. If a large part of the floor is hollow, laying over it is not worth the risk.

Level check

Run a long straight edge or aluminium level across the floor in several directions. Note dips and high spots. New tiles, especially large formats, will follow the old floor, so major dips must be corrected with a levelling compound before tiling.

Moisture check

Look for dark joints, salt deposits, peeling skirting or a musty smell. Damp under the old floor will eventually attack the new adhesive. Find and fix the source first.

Preparing the surface

A glazed or polished tile surface is smooth, and ordinary cement mortar does not bond well to it. Preparation is what makes tile on tile reliable:

1. Deep cleaning. Remove all wax, oil, soap film and dirt. Kitchens especially carry a layer of grease that must be scrubbed off with a degreaser and allowed to dry.
2. Roughening. We lightly grind or scratch the glaze with a grinder and suitable disc to give the adhesive a key.
3. Repairing. Replace or fill hollow and broken tiles, and fill deep old joints.
4. Priming. Where the adhesive manufacturer recommends it, apply a bonding primer over the old tiles.

Choosing the adhesive

This is not a job for plain cement paste or a basic tile adhesive. Use a polymer-modified adhesive that the manufacturer specifically states is suitable for tile-on-tile or for low-absorption surfaces. These adhesives bond chemically and mechanically even to vitrified surfaces. Mix according to instructions and do not add extra water to make it easier to spread.

Fitting the new tiles

Joint planning

Try not to line new joints exactly over old joints. Offsetting them slightly reduces the chance of any old crack or movement showing through.

Full coverage

Use the correct notched trowel, comb the adhesive in one direction, and back-butter the tiles, particularly large ones. Lift a tile occasionally to check coverage.

Movement joints

Leave a gap at walls hidden under skirting, and keep any existing movement joints in the structure continuous through the new floor.

The height problem: doors, thresholds and drains

Tile on tile raises the floor. Plan for this before you start:

• Doors may need trimming at the bottom. It is easier to remove and trim them before fitting.
• Thresholds between rooms may need a marble or granite threshold strip with a slight bevel to hide the level change.
• Bathrooms need special care. The new floor must still slope to the drain and stay below the room outside. Floor trap levels may need adjustment.
• Kitchen platforms and fixed cupboards lose a little height under the counter.
• Skirting usually has to be removed and redone.

Tile on tile on walls

Walls can also be re-tiled over old tiles, which is common in bathroom and kitchen renovations. The same rules apply: tap test, degrease, roughen and use the right adhesive. Check that the added thickness does not cause problems around switchboards, taps and mirror edges. Plumbing outlets may need extension pieces.

Checklist before you decide

1. Tap test done and hollow tiles marked.
2. Level checked across the floor.
3. No dampness or leaks.
4. Door, threshold and drain heights worked out.
5. Correct adhesive bought for tile-on-tile use.
6. Surface degreased and roughened.

Saving the mess, keeping the quality

Done properly, tile on tile can give you a new floor with far less disruption, especially in occupied homes and running shops. Done carelessly, it creates a new floor sitting on an old problem. If you are unsure, we can inspect the existing floor and tell you honestly whether to lay over it or break it. Send photos on WhatsApp to 9468916422, read about our tile fitting and flooring service, or contact us for a site visit.