Electric underfloor heating

In an electric underfloor heating system, a series of electrical wires or heating mats are installed beneath your flooring. This guide explains everything from how it works to what happens during installation.

Installing electric underfloor heating can be a good way of warming up floors you walk over in bare feet, such as in a bathroom, or even be an alternative to radiators. But underfloor heating can be disruptive to install, particularly in existing rooms. One way to keep disruption to a minimum is to do it at the same time as other refurbishments  

Find out more about the pros and cons of underfloor heating from people who've already had it installed. 

Looking for a professional to help upgrade your heating system? Make sure you use a Which? Trusted Trader. All our traders have passed our rigorous vetting procedure carried out by our trading standards professionals.  

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How do electric underfloor heating systems work?

Electric underfloor heating is usually placed on top of a layer of floor insulation, to ensure the heat travels upwards rather than down. This is first laid on a layer of screed (made of sand and cement) or suspended timber (floorboards on joists), to ensure the surface is completely flat.

The heating wires are then connected to your mains supply. The system will also include a sensor to help regulate the temperature. You can then use a thermostat to control the temperature and pre-set the system to turn on or off. 

You can buy underfloor heating mats and wires from DIY stores such as B&Q and Wickes, as well as from specialist retailers.

Electric underfloor heating systems vary in terms of wattage, from around 100W to 200W per square metre. The system and wattage you choose will depend on:

• The size and shape of the room
• How well insulated the room is
• What the flooring below it is like
• The type of flooring you'll have on top. 

What temperature does electric underfloor heating run at? 

Electric systems run at approximately 25-31°C, on average, depending on how warm you set them. 

It will depend, in part, on the type of flooring you want to have on top of it – such as carpet or laminate – and what the floor underneath is like. Underfloor heating systems typically come with a thermostat to help you control the temperature. 

Electric heating thermostats

Electric underfloor heating thermostats are usually wall-mounted in the same room as your underfloor heating. They let you adjust the temperature of your underfloor heating to the level you prefer, helping ensure the system runs efficiently and keep costs down. You'll need a separate thermostat for each room you have underfloor heating in. 

Types of thermostat

There are a few different types of thermostat, ranging from simple to sophisticated. In some cases, you may be able to choose the type of thermostat that's included with your system; you'll probably pay more for a smart thermostat than a basic one. 

• Manual dial/traditional thermostats -  these simply models are controlled manually, by turning a dial, for example.
• Programmable thermostats - these allow you to select when you want the underfloor heating to turn on and off, and the temperature you want it at (you may want different temperatures for different times of day, for example).
• Smart thermostats - these let you manage your underfloor heating from a distance, typically using a smartphone app, and may have more nuanced setting options. They can also be handy if, for example, you head off on holiday and realise you've forgotten to turn the system off.  

When setting your thermostat, bear in mind that underfloor heating takes longer than radiators to heat up, so if you want toasty tootsies first thing in the morning, set it to turn on at least half an hour before you get up. 

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Where can electric underfloor heating be installed?

You can have electric underfloor heating installed anywhere you can get an electrical power supply. Electric systems are less bulky than water underfloor heating systems, so the floor might not need to be raised in the same way. This makes electric underfloor heating more convenient and often cheaper to install than water-based systems. But, because electric underfloor heating can be more costly to run and less powerful than water-based systems, it's generally better suited to smaller rooms, such as bathrooms.

The majority (65%) of people we spoke to with electric underfloor heating had it installed in just one room, most commonly in a bathroom (64%), followed by the kitchen (34%)*.

How do you install electric underfloor heating?

It's possible to lay electric underfloor heating yourself, though you'll need a qualified electrician to connect it up to your electricity supply and add a thermostat. 

However, if you're not that confident with DIY, we'd recommend using a professional. They'll be able to consult on the suitability of your rooms for electric heating and the best type as well as preparing and insulating your floors and installing the wiring. They'll also be able to draw up a plan for where wiring will go – for example, underfloor heating wires shouldn't go under any permanent fixtures or fittings. 

You can use Which? Trusted Traders to find an underfloor heating installer in your area. We rigorously check the backgrounds of all the traders and companies we recommend, so you don't have to.

Electric underfloor heating mats vs wires

Underfloor heating comes in two main forms:

• Mats. With these, a series of wires are attached to a mat at regular intervals. The mats can be cut to size (avoiding cutting through the wires themselves) and laid across a smooth and level floor. The flooring is laid on top of this. Mat-based systems can be easier to install, but they may not be as good for small or irregularly shaped rooms, as you have to work around the placement of the wires. 
• Loose wires. These can be laid however you want them, making them a lot more flexible if you have an awkwardly shaped room. However, you'll need to ensure the wires are evenly spaced, or the heat won't be evenly distributed across the floor. 

Preparing your floor and laying the wires

When installing electric underfloor heating, it's important that your floor has been prepared and insulated in the best way for the floor type and its location in your home. Then it should be a simple case of laying and taping down the wires.  

A self-leveling compound (such as screed) can also be applied to the top to keep the wiring in place, but whether this is needed depends on how even the floor is already, and what flooring you'll be putting on top. Keep in mind that the type of floor you put on top will also affect the type of wiring you use, and therefore the cost. 

A qualified electrician will need to connect it up to your electricity supply and install the thermostat.

How much does electric underfloor heating cost to install and run?

Electric underfloor heating is generally cheaper to install than water underfloor heating because installation is less intrusive, especially if it's being retrofitted. Check our guide to underfloor heating costs and installation to find out the typical prices for different scenarios, based on information from the Royal Institute of Chartered Surveyors (RICS).

But it will typically be more expensive to run than either a water-based underfloor heating system or conventional central heating. 

The running costs for underfloor heating systems will vary considerably, as they are impacted by factors such as:

• Home insulation
• The size of the area to be heated
• How long the system runs for
• Your energy tariff. 

As a rough guide, based on manufacturers and Beama estimates, we estimate that running underfloor heating for four hours a day in a 2.5m2 bathroom would incur monthly electricity costs of around £4-6

*In December 2021 we asked 119 Which? members with underfloor heating about their experiences with it in the past five years.