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Underfloor heating explained

Electric underfloor heating

By Liz Ransome-Croker

Article 1 of 4

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Electric underfloor heating

Is electric underfloor heating right for your home? Read on to find out how it works, how it's installed and how much it costs to buy and run.

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.

If you want to know what owners consider to be the benefits and drawbacks of underfloor heating, jump straight to our pros and cons page.

How does an electric underfloor heating system work? 

Electric underfloor heating systems vary in terms of wattage, from around 100W to 200W per square metre. But 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. 

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 and it 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.

What temperature does electric underfloor heating need to be at?  

Electric systems run at approximately 25-31°C, on average. But 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. 

Where can it be installed? 

You can have it installed anywhere you can get an electrical power supply. But because electric underfloor systems can be more costly to run and less powerful than water-filled systems, they're generally better suited to smaller rooms, such as bathrooms.

The majority (66%) of people we spoke to with electric underfloor heating had it installed in just one room, most commonly in their bathroom (63%), followed by the kitchen (32%)*. 

How do you install electric underfloor heating mats or wires? 

A series of wires are attached to a mat at regular intervals. The mats can be laid across a smooth and level floor, and insulation placed on top. 

Loose-wired systems don't come on a roll, so can be laid however you want them. This makes them a lot more flexible if you have an awkwardly shaped room. However, you'll want to ensure the wires are evenly spaced, or the heat won't be evenly distributed across the floor. 

Because electric systems are generally quite thin and simple to fit, they can be easier and less hassle to install in an existing room than a wet heating system, which requires some space for pipework and could involve the floor being raised.

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 installation 

Electric underfloor heating is generally better for smaller spaces, and it's much easier to retrofit. 

This is partly because electric systems are less bulky than water-filled systems, so the floor might not need to be raised in the same way. 

Just like with water 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. We would advise getting in an expert to consult on this.  

Next, the installer draws up a plan for where the electric mats or loose wires will go. They shouldn't go under any permanent fixtures or fittings. Then it's 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 it in place, but it 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 electrical mat you use, and therefore the cost. 

A qualified electrician will need to connect it up to your electricity supply and add a thermostat.

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

Electric underfloor heating is typically more expensive to run than water underfloor heating and a conventional central heating system. But it will generally be cheaper to install because installation is less intrusive, especially if it's being retrofitted.

See our guide to underfloor heating costs to find out the latest prices from RICS.

*In November 2017 we asked 104 Which? members with underfloor heating about their experiences with it in the past five years.

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