Find out how underfloor heating works, the different options available, what costs are involved and whether it’s right for your home and lifestyle.
Image: Pergo (0844 811 8288; pergo.co.uk)
Once used predominantly in kitchens, bathrooms or the occasional hallway, under floor heating (UFH) is now aviable choice when it comes to heating larger spaces – and even the whole house. As well as being cosy and warm underfoot, it also offers the benefit of radiant heat; warmth rises up to fill the entire room, with an even temperature and no cold spots.
‘One of the biggest attractions is that it’s completely invisible, with no need for radiators taking up your wall space,’ adds Stuart Wisbey, director at the Stone & Ceramic Warehouse (020 8993 5545; sacw.co.uk). ‘It is also particularly advantageous in spaces such as wet rooms, as floor moisture is quickly evaporated.’
Although there are many systems on the market, they all fall into one of two basic types –electric or wet. An electric system, usually in the form of very thin wire or matting, works independently from central heating, and causes less disruption if you’re retrofitting on an existing floor. A wet system, on the other hand, is connected to the main central-heating source and works by circulating warm water through plastic pipes installed under the floor.
Image: Quick-Step (+32 56 675 211; quick-step.co.uk)
There are conflicting figures about the eco benefits and savings for under floor heating, depending on the type of piping laid and the insulation used. It can take a couple of hours to heat up a room using under floor heating, whereas a radiator might take only 20 minutes.
However, radiators cool down a lot faster. The solution is to leave under floor heating on all day at a moderate temperature, such as 16°C, which uses less energy than a radiator having to heat a room from cold.
An electric system can be more expensive, but a programmable timer – such as the 3iE Energy Monitor thermostat by Warmup (0845 345 2288; warmup.co.uk) – can be used to optimise performance. Plus, as it runs independently from central heating, you can warm a specified area without having to heat the whole house.
Image: Hydronic underfloor heating system designed by Nu-Heat
Generally, under floor heating offers more than enough warmth to be used as a single form of heating, but its capabilities will be dictated by factors such as the floorcovering and building insulation levels. Ask your installer about finding out the property’s individual thermal performance, so you can calculate the amount of heat you need to generate. All installations should be tested before the floor finish is laid.
Electric underfloor heating (dry system)
Also known as a dry system, electric underfloor heating is installed directly under a floor covering. It’s ideal for single-room installations, where a sub-level is already set. The wire or matting is very thin (about 3mm) and causes little disruption to the existing room. And it’s not restricted to use under floors; an electric underfloor heating system can be installed on a wall and seating in a shower and wet room.
All electrical connections must be made and tested by a qualified electrician in order to comply with building regulations. Because the heating element sits directly under the flooring, circuits are easily accessible if they need to be repaired. A disadvantage of this type of underfloor heating is that it can be more expensive to run than a wet system, and the Energy Saving Trust doesn’t recommend it for use in large areas. Roll-out heating mats start at £50 per sqm, but can get less expensive the more you buy. A loose-fit kit will cost from £100 per m.
Image: Stone & Ceramic Warehouse (020 8993 5545; sacw.co.uk)
Water based underfloor heating (wet system)
A water-based underfloor system consists of a series of pipes connected to a boiler, which circulate warm water throughout the floor to heat a space. Generally used in new-builds or extensions, it is best suited to new floor constructions, which can be designed to hold the pipework and be adequately insulated. It’s ideal for an open-plan space or whole-house system, and can be fitted to a solar water-heating system.
A wet system can have a slower warm-up time than other heating (depending on the system) but, on the plus side, it also takes longer to cool down. A heating engineer or specialist will complete the water based underfloor heating installation, which can run to thousands of pounds if it’s a whole-property system. But problems tend to be extremely rare, and pipes are designed and tested to have a 50-year life expectancy. Just be aware that retrofit can be difficult, and floors may have to be elevated to allow for pipework. Prices start at just over £100 per sqm.
Image: Junckers (01376 534 700; junckers.co.uk)
Choosing your flooring
Underfloor heating is compatible with a wide range of floorcoverings, including carpet, providing the combined thermal resistance of the carpet and underlay is less than 2.5 tog. The thicker the product, the longer it will take to heat up and cool down. ‘The material needs to be expertly installed,’ says Jason Cherrington, director of Lapicida (020 3012 1000; lapicida.com). ‘You have to wait for the screed to dry properly and then the UFH needs to be run to test it, as thermal movement can cause certain types to crack. Laying the floor tiles is relatively quick and shouldn’t take more than a day per 10sqm for a proficient tiler.’
Engineered boards are also a popular option among renovators and self-builders because they are less likely to warp. ‘It is one of the best materials for use with UFH,’ says Russell Calder at Havwoods. ‘Natural, warm to the touch and a good conductor of heat, the majority of engineered boards are perfectly suited for use with UFH. This is particularly true of those with a solid-oak lamella – the top layer of an engineered plank.’
Image: Havwoods (01524 737 000; havwoods.co.uk)
- Underfloor heating is more efficient and cost effective if fitted above insulation, as it reduces downward heat loss. Ensure the rest of your house is well insulated, too.
- Stone, porcelain, slate and ceramic are compatible with underfloor heating, and have good thermal conductivity to provide a quality heat output. Thicker stone floors will take more time to warm up, but will retain heat for longer.
- If you’re looking for wood flooring, check suitability with your supplier, or consider engineered-timber boards.
- Most luxury laminates and vinyls are compatible, too, and you can also use carpet, providing that the combined thermal resistance of the carpet and underlay is less than 2.5 tog – check the details with the manufacturer.
- As a general rule, flooring that is compatible with UFH can be used with both wet and electric systems.
- The expense may outweigh the advantages if you need to remove and rescreed a concrete floor to install a wet UFH system.
- Choose a system that comes with an extended warranty as standard.
Words: Jo Messenger