Heat your house, keep your toes toasty, and save money on your energy bills into the bargain. Our guide to underfloor heating tells you all you need to know.
The practical choice
In Scandinavian countries as many as 80 per cent of homes are warmed by underfloor heating – and Britain is catching up fast. It’s no surprise that underfloor heating is growing in popularity. Relatively cheap to install, economical to run and with little maintenance required, it makes practical sense. It also frees up wall space normally dedicated to radiators and can now be installed under virtually any type of floor. It’s generally considered to be a more eco-friendly option than radiators too, in part because of the way it heats a space. Rather than heating from the top of the room down (as radiators do), underfloor heating makes the lower part of the room warm first.
It’s deliciously toasty underfoot – around 25oC on average – which makes a room feel instantly cosy. And because it has a lower running temperature than radiators you can save on fuel bills too, though this does depend on the type of system.
Types of underfloor heating
There are two main types of underfloor heating systems: hot-water (or wet) systems, and electric (or dry) systems.
Wet systems use warm water, much like your central heating system. The water is pumped through tiny pipes that are laid on your subfloor and then covered with a special heat-conducting screed, which, once warm, retains its heat efficiently. Wet systems can be as much as 30 per cent more energy-efficient than radiators, because they use water at a lower temperature. They can also be integrated with your existing heating system, so you can choose underfloor heating for some rooms and radiators for others. On the downside, because they have to heat through a layer of screed, wet systems can take a long time to heat up (as much as two hours) and also take longer to cool down, so getting the temperature right can sometimes be a challenge.
Wet systems are a great choice if you’re building from scratch, or undertaking a major renovation, but are generally a hassle to install under an existing floor, as you’ll need to rip up the floor and pour screed material. Wet systems tend to be expensive over small areas, too. Expect to pay from £25-£30 per sqm depending on the surface area. Traditional electric systems consist of cables that, similar to a wet system, are laid in screed. Modern versions, which are much thinner and simpler to install, are more like mesh mats or a roll of ribbon and, much like a carpet underlay, are simply spread across your existing floor (on top of an insulated board) and then linked to your power supply. There’s no screed involved and they can be laid under any floor types, including timber, or on top of old flooring. Electric systems tend to be cheaper to install than wet systems (expect to pay from £15 per sqm), and much less hassle, so are a better option if you aren’t planning a major renovation. They also heat up more quickly because they’re not covered with screed, so are more responsive – some manufacturers cite three- minute response times. But electric systems can be more expensive to run than wet systems and won’t link with your general heating system so you’ll need to set up a separate thermostat and timer.
The main developments in the underfloor heating sector are focused on making the product thinner, more robust and easier to install. ‘What we call Generation Four systems are more flexible and more resilient,’ says Speedheat chief executive Pieter Jansen. ‘They’re designed to take movement so can be laid directly under floor coverings. Being so close to the surface the element needs to be safe and also very resilient to chemicals such as cleaning detergents – many systems are now so thin that you simply can’t feel them, even under carpet.’
Chelmer Heating Services has recently released Retromat, a very low-profile wet system. Just 24mm in depth it is much thinner than traditional wet systems, which are about 100mm. Like traditional systems it is laid in screed, but you’ll lose little in the way of room height.
Electric systems are becoming even slimmer. Allbrite’s Ribbon system is just 1.8mm thick and can be laid on any subfloor and under any floor covering. It is designed to be flat and wide, allowing comprehensive coverage and meaning that it can run at lower temperatures and still keep the room warm.
Thermostat controls are also becoming more sophisticated and it is now possible to find underfloor heating that can link in to computerised intelligent home systems – allowing you to adjust temperature remotely and set up complex programmes based around your holidays and other day-to-day requirements.
Where can I use underfloor heating?
Underfloor heating is generally considered the perfect solution for warming up cold flooring materials such as flagstones in the kitchen or tiled bathroom floors. Bear in mind that the thicker the stone is, the longer it will take to heat up.
Technological developments that can keep a system running at a lower temperature mean you can now use underfloor heating with hardwood and laminate floors. But before installing, check with both the flooring supplier and heating installer. Many suppliers will recommend a specific brand of underfloor heating and it’s generally a good idea to listen to their advice.
Because underfloor heating is getting slimmer, you can now also install it under high-quality vinyls, such as Amtico (amtico.com) or Karndean (karndean.com), and even carpet – though you need to ensure the carpet plus underlay is less than 2.5 tog.
Underfloor heating is not limited to ground-floor use either. For most modern systems you don’t need a concrete subfloor, so it can safely be used above ground-floor level. Some systems can even be laid around sound insulation (try Speedheat) – great if you’re trying to minimise noise from a first-floor flat.
As long as you have some DIY expertise, underfloor heating is relatively easy to install yourself. With electric systems you’ll need to lay a flat base, generally an insulated wood board, then roll out and fix the heating mat before laying your floor in the usual way. Always ask a qualified electrician to do the final connection and approve the installation. For wet systems you’ll need a similar flat base floor on which to lay the product and then a specialised heat-conducting screed must be put down on top of the product before you lay your floor coverings. You’ll need a qualified plumber to make the final connections and CORGI registered workmen for any connection to the boiler system – visit trustcorgi.com for a searchable database of CORGI-registered tradespeople.
One of the benefits of underfloor heating is that it requires virtually no maintenance. There are no moving parts and wet systems are protected by the surrounding screed. Electric systems are designed to be equally robust and most manufacturers suggest 15 years is the minimum expected lifespan; some will last as long as 30 years. Many systems come with very long warranties (10 or 15 years); ask about guarantees and warranty life before buying. For further information, visit the Underfloor Heating Manufacturers’ Association website at uhma.org.uk.
Robbens Systems: www.underfloorheating.co.uk
Speed Heat UK: www.speedheat.co.uk
Encompas Ltd: www.encompas.co.uk
Devi Ltd: www.devi.co.uk
Invisible Heating Systems: www.invisibleheating.co.uk
Total Floor Heating: www.totalfloorheating.com
Nu – Heat: www.nu-heat.co.uk
Words: Trish Lorenz
Picture1: Continental Underfloor Heating
Picture2: Flexel’s EcofilmSet
Picture3: Speedheat’s screeded heating system
Picture4: Profoil underfloor heating system