Electric Underfloor Heating as a Primary Heat Source

The "electric underfloor heating can't be primary" myth

Search this question and most pages give you the same hedge: electric underfloor heating is only a top-up, you need a wet system for primary heat. Forum threads repeat it. Plenty of competitor blogs repeat it too, because it lets them sell you a water system or a boiler upgrade.

Here is the honest version. That advice is correct for one type of electric heating and wrong for another. Lumping every electric system together is where the bad advice comes from. The type you buy decides whether it can be your only heat, not the words "electric underfloor heating" on the box.

Why thin mats can't but the ribbon can

A standard electric mat is a single heating cable woven back and forth across a sheet, or a thin foil with a cable running through it. There are not many heating elements packed into the floor. That works fine to take the chill off a small tiled bathroom. It does not put out enough heat across the whole floor to carry a room on the coldest day, so it gets sold as a comfort top-up next to your radiators.

The EkoBuild Ribbon is built differently. It uses an amorphous metal ribbon with 300% more heating elements than a standard cable system. More elements spread across the floor means more even, usable heat coming up into the room, and a lower surface temperature doing it. That density is the whole reason the ribbon can be a primary heat source where a cable mat cannot.

Floor warming and primary heating are not the same thing

This is the distinction that decides everything else, and almost nobody makes it before they buy.

Floor warming is exactly what it sounds like. The system is installed to take the chill off a cold floor and make it more comfortable underfoot, while radiators or another system do the actual heating. You see it in individual bathrooms, kitchens and small areas. It is a comfort product, and it doubles your running costs, because you are now paying to run two heat sources instead of one.

Primary heating has a much bigger job. It has to heat the floor, heat the room, and hold a comfortable temperature throughout the property. If the underfloor heating is doing that without radiators making up the difference, it is the primary heat source.

People associate electric underfloor heating with background warmth because most of the systems they have seen only cover a limited part of the floor. Those were chosen as a comfort product, not designed to heat a room. That is a decision someone made, not a limit of the technology.

So the question to ask is not "does this house have underfloor heating?" It is: has this underfloor heating been designed to warm the floor, or has it been designed to heat the home?

Three things that decide whether it works

Even a system designed for primary heating can perform poorly if it is not installed correctly. Three things matter as much as the product.

The property. A well insulated house holds heat far better than a draughty, poorly insulated one. Insulation is not a detail here, it is half the job.

The amount of floor covered. Install too little heating and expect it to warm a large room, and it will struggle. That is what the coverage rule is for.

The complete installation. The insulation beneath the ribbon, the flooring above it, where the floor sensor sits and how the thermostat is set all change how the system performs.

From the installations we have seen, poor performance is usually blamed on underfloor heating as a technology when the real problem was insufficient coverage, unsuitable insulation, the wrong controls, or shortcuts during installation. That is why we do not just sell a roll of heating and tell people it will work anywhere. The property, the flooring and the intended use have to be understood first.

The 70% coverage rule

Whether the ribbon is your only heat comes down to one number: how much of the floor it covers. Cover enough of the floor and the room has a big, gentle radiator built into it. Cover too little and you are back to a top-up.

You do not heat under the kitchen units or the bath, so a real room rarely needs 100%. The free Room Designer works out your usable floor area and tells you the coverage your layout gives, so you know before you buy whether you can lose the radiators.

Will it actually keep the room warm?

Yes, on two conditions: enough coverage, and decent insulation under the ribbon. The ribbon runs at 150W/m² across a wide spread of the floor. At 70%+ coverage that turns the whole floor into a low-temperature heat source, which is a more even and comfortable warmth than a single hot radiator in one corner.

Insulation is the part people skip and then complain about. Without it, a chunk of your heat sinks down into the subfloor instead of rising into the room. Lay Therm-All insulation under the ribbon and it pushes the heat upward, so the room warms faster and holds it. Get the coverage and the insulation right and the ribbon carries the room without help.

What it costs to run, the honest answer

This is the real objection, so here it is straight. Electricity costs more per unit than gas, so if a poorly insulated room ran the ribbon flat out all day, it would be dear. That is the worst case, and it is avoidable. Three things keep the running cost down.

• Insulation. Therm-All under the ribbon means you heat the room, not the ground. Less wasted energy, lower bills.
• The ribbon only sips power once it is warm. Getting a room up to temperature draws the most. After that, the ribbon only draws power for about a quarter of each hour to hold the heat. It is not running flat out all day.
• Smart scheduling. The touch screen thermostat heats rooms when you use them and lets them coast when you don't, so you are never warming an empty house.

Get those three right and electric underfloor heating as your main heat is far cheaper to run than the worst-case figure the doubters quote. And there is one more lever that the gas vs electric argument ignores completely.

Pairing with solar and battery

Electric heating has one advantage gas never will: you can make the electricity yourself. Pair the ribbon with solar panels and a home battery and the maths changes.

Solar covers your daytime heating for free when the sun is out. The battery stores cheap off-peak power overnight, then runs the floor through the morning on electricity you bought at the low rate. On the right tariff, a well-insulated room on the ribbon can cost close to nothing to heat. EkoBuild supplies solar PV and battery storage as well as the ribbon, so the heating, the panels and the battery can come from one place and one plan.

Which rooms and floors suit it

The ribbon works as primary heat across the house because it goes under almost any floor finish:

• Carpet, including as a primary heat source. Most electric systems cannot do this. The ribbon can, so bedrooms and lounges are on the table, not just hard floors.
• Laminate and engineered wood
• Vinyl and LVT
• Stone and tile

Open-plan living rooms, kitchen-diners, bedrooms and bathrooms all suit it. It works on a single floor or whole house, upstairs and down, because it is 1.8mm thin and tapes to the subfloor with no screed and almost no change to floor height. If you are renovating and ripping up floors for a wet system is a non-starter, this is the version that fits. There is more on that in our guide to underfloor heating with no screed.

Losing the radiators

This is the part people underrate. At 70%+ coverage the ribbon is the heat source, which means the radiators come off the wall for good. You get the wall space back in every room. No cold corners, no radiator to work the furniture around, no dust traps, and a quiet, even warmth from the floor up instead of hot air rising off a panel.

It also means one less system to maintain. No radiators, no rads to bleed, and on a full electric setup, no gas boiler and no annual service. The ribbon carries a 15-year warranty, so the heat source you are trusting your whole room to is built to last.

How to size it for primary heat

Sizing is the bit that decides if this works, and it is the bit you should not guess. You need to know your usable floor area, the coverage your layout reaches, and that it clears 70%. Do that and you can confidently take the radiators out.

• Map the room in the free Room Designer. It works out usable area, coverage and the exact ribbon layout in a couple of minutes.
• Plan for 80%+ coverage where you can, especially in colder or north-facing rooms.
• Order the matching 1m Ribbon roll for open floors, and put insulation under it.

Want the full background on how the system works first? Start with our complete electric underfloor heating guide.

More of Russell's answers, including what it costs to run and how the four technologies compare, are on the answers page.

Full transcript

This is what Russell says in the video, in full. It is published so you can read it rather than watch it, and so search engines and AI assistants can read it too.

Electric underfloor heating as primary heat: FAQs