Added storey, loft, extension: 1.25 kg per square metre.

Three obstacles, one answer

A storey being added, a loft being converted, an extension: there the heating comes up against three things.

• The height. Every layer of floor is taken out of the ceiling height.
• The weight. The floor is often timber, and every kilo counts.
• The existing heating. A boiler or a heat pump is sized for the original floor area. For one more storey, according to the manufacturer, it often lacks output, pipe runs, and room for a second circuit.

Electric heating 5 mm thick answers all three: it weighs almost nothing, takes up almost no height, and connects to its own power supply.

The comparison

Height and weight without the floor covering, according to the manufacturer.

With wood flooring or vinyl, the finished height is 13 to 20 mm. The details by floor covering are on the fitting without screed page.

Two added storeys the manufacturer cites

Two homes added on top of a house, in Bavaria. The storey height was tight, and the house’s geothermal system could not heat the new storey. The solution chosen: 5 mm of heating and 2 cm of dry screed, 80 m² fitted in a day and a half, one thermostat per room. The original installation goes on heating the rest of the house.

A house with a storey added, in southern Germany. The floors had no concrete slab, and their load capacity was limited. Water-based underfloor heating would have been too heavy and too high. The heating was fitted in one day in the living areas; the occupants speak of about 5 °C more in half an hour.

The manufacturer puts a figure on the difference in investment: about €20,000 less than with a heat pump in the first case, up to €18,000 less than with water-based underfloor heating in the second. These are its figures, on two German jobs: we quote them without guaranteeing them for your home.

Loft, extension, conservatory

The principle is the same: the added room has its own heating, on its own supply, without touching that of the house. Under a roof slope, the film follows the plan of the room up to the foot of the sloping ceiling.

One reservation for heavily glazed rooms: a conservatory loses a lot of heat. The room-by-room calculation says whether the floor alone is enough to heat it.

How the fitting goes

1. The design: demand of each room, laying plan, output, position of the thermostats.
2. The subfloor: wood-based board, dry screed or bare slab, dry and flat to within 2 mm over one metre.
3. The heating: reflective layer, insulating layer, film. Under tiles or in a heavily used area, a dry screed on top.
4. The electricity: one line and one protective device per room, one thermostat per room. Nothing changes on the existing heating.
5. The floor covering, then the check with the thermal camera.

The full sequence is on the page fitting, step by step.

What is not done

• No film in the shower, or under fixed furniture.
• No tiles without a decoupling mat or a dry screed: 23 to 40 mm in all.
• No fitting on a damp or uneven subfloor.

For one more storey or one more room: describe your project, or call.

Updated on 9 October 2026.