Microcement Over Tiles | When It Works and When It Fails

01 The short answer

Yes, and that is rather the point

Microcement is applied two to three millimetres thick over what is already there. Tiles are one of the surfaces it is designed for, and going over them is the main reason people choose it over a retile.

What you save is not really the tiling. It is the rip-out: the skip, the dust, the days with no bathroom, and the discovery of whatever is behind the tiles once they are off.

But it goes over sound tiles, not any tiles. Microcement is a finish, not a repair. It follows what is underneath and it inherits every problem there.

The honest version

A contractor who will microcement over anything you point at is not doing you a favour. The four checks below take twenty minutes and they decide whether the wall is still fine in five years.

02 The four checks

What has to be true before anyone starts

The tiles are stuck down

Tap across the whole area with a knuckle or the handle of a screwdriver. A solid tap is fine. A hollow, drummy note means that tile has lost its bond, and a loose tile under microcement is a crack waiting to appear. They come off and the hole gets made good.

Nothing is wet

A damp wall behind tiles stays a damp wall under microcement, and now it is sealed in. If there is any history of a leak, staining, or a musty smell, that gets found and fixed first. This is the one we most often have to say no to.

Nothing moves

Timber floors, boarded walls and anything that flexes underfoot will telegraph a crack through eventually. Movement gets stiffened up, or the job gets a full decoupling layer. Fibreglass mesh through the base coat handles the small stuff, not a bouncing floor.

The surface is flat enough

Microcement is two millimetres thick. It will not level a floor, take out a dip, or hide a tile that sits proud of its neighbours. Big variations get levelled first, as a separate step with its own cost.

03 Grout lines

What happens to the joints

This is the question everyone asks, and fairly — a grid of grout lines ghosting through a seamless finish is the classic bad microcement job.

Narrow, shallow joints on a modern wall tile disappear into the primer and base coats without any special treatment. Wider or deeper ones get filled flush first and left to dry, so the base coat is not bridging a gap it will later sink into.

The part that actually prevents ghosting is the fibreglass mesh bedded into the base coat. It spreads any small movement across the whole surface instead of letting it concentrate along a joint line. On a tiled substrate we would not leave it out.

Deep textured tiles, mosaics with a lot of joint, and anything with a heavy relief are a different case. Those usually want a levelling coat first, and on a floor they sometimes genuinely are better off coming up.

The preparation, in order

Degrease properly — soap residue and limescale on old bathroom tiles are the commonest cause of adhesion failure.

Key the glaze, either mechanically or with the right primer for glazed surfaces. A quartz-filled primer gives the base coat something to hold.

Fill the joints, let them dry, then base coat with mesh through it.

Two finish coats, then two or three coats of sealer, depending on the room.

04 Where it fails

When we would tell you not to

A shower with no tanking behind the tiles

Microcement is water-resistant once sealed, but it is not the waterproofing. If the existing tiles were fitted straight onto board with nothing behind them, going over the top seals the problem in. That one gets stripped.

Tiles that are already lifting

More than the odd loose one and you are finishing over a substrate that is on its way off the wall. Pulling them is cheaper than doing the room twice.

A floor that flexes

Stand in the middle and rock your weight. If you can feel it move, a two-millimetre coating will not stop it.

Height you cannot lose

It adds two to three millimetres. Usually nothing, occasionally the difference between a door that clears the floor and one that does not. Check thresholds before, not after.

Costs, per square metre, and why small rooms cost more: what a microcement bathroom costs.

05 Questions

What people ask

Can you microcement over bathroom tiles?

Yes, and it is the most common version of this job. Walls, floor, shower tray and all, with no grout lines anywhere afterwards. The tanking question above is the one that decides it.

Do the grout lines show through microcement?

Not if the joints are filled and the base coat has mesh through it. They show through when someone has skipped one of those to save half a day.

Can you microcement over floor tiles?

Yes, on a solid floor. On a suspended timber floor it depends entirely on how much the floor moves, and that is a judgement made on site rather than from a photograph.

Does microcement work over underfloor heating?

Yes, and better than tile does — it is thinner, so the heat comes through faster. The heating has to be commissioned and cycled properly before the microcement goes on, and the screed has to be fully dry.

How long does it take to microcement over a tiled bathroom?

Four to seven days on site for a normal bathroom. It is five to seven layers with drying time between them, and there is no honest way to compress that.

Is it cheaper than retiling?

Not usually on the invoice, often yes on the whole job, because you skip the rip-out, the skip hire and the making-good behind the old tiles.

Can you microcement over tiles yourself?

Kits exist. The preparation is the part people get wrong, and it is the part that decides whether it lasts. If you want to learn it properly we run training courses.

06 Start

Send us a photograph of the tiles

A picture of the room and rough measurements is enough for us to say whether it is a candidate, and to be straight with you if it is not.

Start a project See the work

More on microcement, bathrooms and wet rooms and what it costs.