Electric underfloor heating under tiles

What the rule says

In Wallonia and Flanders, the rule limits direct electric heating, and names electric underfloor heating. Wallonia: 2,500 W at most per home up to 150 m², then 15 W per additional m², on any fitting, appliances already in place included. Flanders: 15 W at most per m² in a renovation subject to a permit or a notification with an architect; in an extension, the cap is calculated on the extension alone. Brussels: we have not found a cap. One room remains possible; a whole home, not within these limits.

In Luxembourg, direct electric heating cannot be the main heating of a building that is new, extended or converted. Partial heating remains possible: the regulation cites the bathroom.

In the Netherlands, a heating system that is fitted or renewed must reach a performance that direct electricity does not reach. The guide published by the public agency RVO rules out electric underfloor heating as main heating; the agency’s page allows local electric appliances controlled room by room. For a room heated as a supplement, the official documents point towards local heating being allowed, without naming electric underfloor heating: to be confirmed by the municipality.

The rule, country by country, with the texts

The short answer

Yes, carbon underfloor heating can be fitted under tiles. But a tile is never glued straight onto the film: between the two there has to be a decoupling mat, or a dry screed. That is the manufacturer’s rule, without exception.

Two ways of doing it

	On a decoupling mat	On a dry screed
From bottom to top	existing floor, 5 mm heating, mat, adhesive, tiles	existing floor, 5 mm heating, dry screed of 18 to 23 mm, adhesive, tiles
Height added	23 to 38 mm	35 to 40 mm
What for	renovation where height is limited, bathrooms, hallways	living room, entrance hall, large tiled areas, large formats
Worth knowing	the thinnest solution; slightly less efficient, according to the manufacturer, than dry screed	the safe solution for natural stone and tiles of 60 cm and more

For comparison, the manufacturer gives 45 to 65 mm for water-based underfloor heating cast in a screed, tiles not included, with weeks of drying.

Where we lay it, and where we do not

We lay it under the clear floor area: where you stand and where you walk, in front of the washbasin, the toilet, the bath.
We do not lay it in the shower, under the bath, under fixed furniture, under the base of the toilet.
The thermostat goes outside the wet area, or in the hallway.
The connection is made by an electrician, with the protection that the country’s standard requires in a bathroom.

How warm underfoot

Under tiles, the manufacturer specifies a more powerful film: 180 W/m², instead of 115 W/m² in the other rooms, because the mat or the dry screed comes in between. The film rises to 44 °C at most; at the surface of the tile, the temperature stays even, between 20 and 24 °C. Feet are warm in about a quarter of an hour.

How long it takes

According to the manufacturer, a bathroom of 8 to 12 m² is done in one day, heating, mat and tiles, if the floor is flat. The tile adhesive keeps its usual setting time. No channels are cut, nothing is poured: little dust.

Just the bathroom?

It depends on the country as much as on the product. The manufacturer designs the system to heat a whole house or a whole apartment, bathroom included, with one thermostat per room; it does not present itself as a specialist in the bathroom alone. In France, we have found no text that prevents a whole existing home from being fitted out. In Luxembourg, the regulation allows direct electric heating only as partial heating, and cites precisely the bathroom; in Wallonia, the cap of 2,500 W per home leaves room for a bathroom and one room, if there is no other direct electric heating. The texts are on the page the rule, country by country.

What is not done

No tile glued straight onto the film.
No film in the shower, under the bath or under fixed furniture.
No fitting on a floor that deviates by more than 2 mm over one metre, without a levelling compound first.

For the other floor coverings: wood flooring, vinyl and laminate. For all the heights: fitting without screed.

Updated on 9 October 2026.

Frequently asked questions

Your questions on this subject.

Why a mat between the film and the tiles?

The tile and the base it sits on do not expand in the same way when the temperature changes. The decoupling mat absorbs these stresses and prevents cracks. On large areas or with large formats, a dry screed does this job.

What height in a bathroom?

According to the manufacturer: 23 to 38 mm with a mat, 35 to 40 mm with a dry screed, including the 5 mm of heating and the tiles.

Can the floor of a walk-in shower be heated?

No. The film stops before the shower: the rest of the bathroom is heated, the shower is left clear. The slope and the waterproofing remain the tiler's job.

Can the old tiles stay?

Yes, if they hold firm and the floor is flat. The heating is laid on them, then the mat and the new tiles.

Is it enough to heat the bathroom?

According to the manufacturer, yes: the room is sized like the others, and the heated towel rail becomes a matter of comfort.

Got a heat pump quote sitting on your desk?

One call, and we send you the Carbosol equivalent for the same area, on one page. Free, and without us calling you back every three days.

Call back within 24 hours on working days Write to us

Audience measurement

Under tiles: possible, never glued straight onto the film.