Underfloor heating guide

What is underfloor heating?

Turning your whole floor into a massive radiator sounds toasty warm and, quite simply, that’s what underfloor heating is. It’s a layer of pipes carrying warm water (or electric coils that heat up), laid underneath your flooring to take advantage of the basic principle of heat waves rising through the air.

How does underfloor heating work?

Underfloor heating warms a room or whole house from the ground up, via a series of pipes (in the case of warm water underfloor heating) or cables (in the case of ‘dry’ or electric underfloor heating) embedded into the floor. The type you choose will depend on a few factors that we’ll discuss in a moment.

How is underfloor heating installed?

First, it depends on whether you’re installing it in a new build or extension, or you’re retro-fitting it in an older house. For a new build or extension, most people install the piping into a layer of screed in the new floor.

If you’re renovating and want to retro-fit underfloor heating into an older house, you can fit it on top of your existing floor. ‘Low-profile’ systems make it easy to get away with minimal disruption to your existing fixtures and fittings.

Can I install underfloor heating myself?

Yes! If you’re a confident DIY-er, it’s reasonably straightforward to install underfloor heating and keep your costs low, but it’s a fairly technical and involved project, so it’s certainly not for beginners.

If you’re installing a water-based system, we recommend hiring a professional plumber as you’ll need to lay water pipes and connect them to your boiler system.
Either way, you’ll need an electrician to connect your new underfloor heating system to your mains electricity and also a sensor for the thermostat.

Benefit of underfloor heating

Here are some of the benefits of underfloor heating:

Luxurious comfort!
There’s just something so luxurious about slinking around your house barefoot – in the UK! Because the entire floor is heated evenly, it’s like feeling the heat of the sun – on your feet.

Better efficiency
Unlike radiators that heat the air via convection, underfloor heating produces radiant warmth. The entire floor is heated evenly, so there are no cold spots, stuffiness or draughts.

Lower running costs
Because heat is distributed evenly around the room, and also because the system covers a much larger area than an individual radiator can, underfloor heating works at a lower temperature (around 40°C compared to 65°C), places less demand on your boiler and therefore can help reduce your heating bills.

More space
Underfloor heating is invisible, so if you’re replacing your radiators with underfloor heating, it frees up wall and floor space, giving you a lot more freedom and flexibility to design your room how you like it. If you’re renovating it can help you transform your property into an open plan living area.

Can underfloor heating add value to your home?

If your property includes underfloor heating (even if it’s just in one room) your home’s asking price will naturally be much more, because it’s a feature most people would love to have.

More hygienic
A warmer floor temperature is like kryptonite to dust mites – and it helps keep the circulation of dust down, so it’s ideal for allergy sufferers. The gentle heat and low humidity also creates a kinder environment for furniture.

Wet systems are compatible with any type of boiler
This is true, as long as your boiler has sufficient capacity.

Easy installation
If it’s a dry/ electric underfloor heating system, it’s possible to install it yourself – as long as you’ve got the tools and skills to do so. If it’s wet, you should definitely get a professional in to do the job.

Works with many different flooring types
You can install underfloor heating below stone, tile, wood or carpet, as long as the carpet isn’t too thick.

Disadvantages of underfloor heating
There are lots of benefits, but what are the downsides?

Expensive to install
Whilst your brand new underfloor heating will help to lower your energy bills, it’s very unlikely that you’ll ever recoup all the money you spent on getting it fitted, especially if you opt for a wet system. This is most suited to new-build properties or if you’re already having some work done on your floor, this can easily be done at the same time.

Electric systems are expensive to run in rooms used all day

One of the most expensive uses for electric underfloor heating is the conservatory. Typically a lounge or conservatory needs a lot of heat and it’s also used all day (compared to a bathroom with two distinct heavy footfall times). For a conservatory that’s used a lot, a wet system may cost more to install and be more troublesome to undertake, but it’s much more worthwhile considering the running costs. We’ll discuss this more in our exploration of the two systems.

Difficult to install in older buildings

Because of the added hoops to jump through (we’ll get to those in a moment), installing underfloor heating in older buildings can take a good chunk of time and cause major disruption.

Takes longer to heat a room

Underfloor heating systems do take longer to heat a room, so it’s important to use a timer so you can plan ahead and to feel cosy when you need to be cosy.

Not compatible with heavy, large furniture

If you really want underfloor heating, you may have to ditch that heavy sofa. The systems can’t sit under particular fittings and furniture items.

Smaller underfloor heating systems may not be worth it

If you’re installing underfloor heating to replace radiators, make sure you avoid buying a smaller underfloor heating system, which will warm the floor but you may end up with the rest of the room still being chilly.

There are two types of underfloor heating:

Electric underfloor heating
Electric underfloor heating is often cheaper and easier to install. But it can be three or four times more expensive to run. It’s best for a small, single room like a bathroom or an en-suite, where you need the heat quickly.

Three choices of ‘dry’/ electric underfloor heating systems:
· Loose wire – best suited to get into every nook and cranny of an awkwardly shaped room.
· Matting – these are cheaper because they’re a uniform size, so they’re also really good for large rooms.
· Foil mat – these are made specially for laminate flooring.

Water underfloor heating

A wet underfloor heating system has continuous plastic pipes (no joints, so no leaks) filled with warm water and powered by your boiler, or a heat pump that’s also under the floor. They easily provide enough heat.

If you’re doing a full renovation, choose a wet system
Because you’re essentially building from scratch, or doing up the whole house, the wet system is your friend. It means you can create enough space in your floor for the thickness of the pipes.

Water or electric underfloor heating?

Because they have a higher heat output, warm water systems are ideally suited to renovations, larger properties or to homes that aren’t well insulated (and if this is you, check out our home insulation guide here).

Electric underfloor heating is perfect for small areas like bathrooms because it heats up quickly when you need it (makes stepping out of the shower a dream).

What types of flooring is underfloor heating best for?

The good news is that underfloor heating is compatible with all types of flooring. Which is best, is up to you:

Stone and ceramic floors
Stone and ceramic floors are best suited to underfloor heating – they are natural heat conductors, warm up quicker and keep heat for longer.

Wooden floors
It’s possible, but check with the manufacturer about safe temperatures. Wood can warp and shrink, especially if the temperature goes above 27°C.

Laminates and vinyl
Again, check the manufacturer’s recommended maximum floor surface temperature to ensure your floor covering is compatible with underfloor heating.

Carpet
Underfloor heating is OK with carpet, but not with thick carpet because it takes too long to warm up.

Concrete
Concrete is on-trend, sleek and modern and well-suited to underfloor heating, because it retains the heat well.

Can you fit underfloor heating in old houses?

Yes, but you need to check how well your home is insulated. If you have poor insulation or single-glazed windows, you will probably still need radiators alongside underfloor heating. You may also need to combine some floor insulation underneath the network of pipes to avoid heat going into the ground.

Check the UK government’s Green Homes Grant to see if you can get financial help to pay for it.

If your energy efficiency is good enough, you can go ahead and choose an underfloor heating system. You will probably need to opt for a low-profile system, with pipes that have a smaller diameter and heat up quicker than regular underfloor heating.

What’s the ideal temperature for underfloor heating?

For most homes it’s about 21°C for general living areas, and about 18°C for bedrooms – it’s healthier to sleep at a lower temperature.

How long does underfloor heating take to work?

It can actually take underfloor heating two or three hours to warm up. This is why a timer is a must, so you can plan when you want to be warm and cosy.

Should I leave underfloor heating on all the time?

Yes, because underfloor heating takes an hour or two to heat up, in the winter it may be more efficient for you to leave it on at a lower temperature throughout the day.

Is underfloor heating expensive?

The most important factor to note is wet systems are cheaper to run, but more expensive to install. Dry systems are cheaper to install and expensive to run. If you’re building a new home, it’s a no brainer to install a wet system because it will save you energy and money. If you’re retrofitting underfloor heating to a single room, it may not be the right time to fit a dry system depending on what else you’re doing. If it’s part of a bigger renovation and you’re opting for a wet system, the cost will probably be worth it.

How much does underfloor heating cost to run?

Electricity costs more than natural gas, which is why a wet system costs significantly less to run than dry. To find out What uses the most electricity in the house? read our article.

How else can I make my home warmer?

Look into upgrading the insulation of your home to help save heat and money. Check out our Floor insulation guide, Cavity wall insulation guide and loft insulation guide here.

Also, if your boiler is more than 10 years old, it’s worth looking into replacing it with a more energy-efficient A-rated model. 

FAQs

What temperature should underfloor heating be set at?

For most homes it’s about 21°C for living rooms and about 18°C for bedrooms.

What are the disadvantages of underfloor heating?

1. They’re fairly expensive to install – best to do it when you’re renovating.
2. Electric systems are expensive to run in rooms used all day.
3. It’s difficult to install in older buildings.
4. It takes longer to heat a room than radiators – so it’s best to use a timer.
5. Wet underfloor heating systems need to be installed by a professional.

What is better electric or water underfloor heating?

Electric is best for a single room like a bathroom or en-suite. Warm water underfloor heating is best for a whole house refurb.

Can you have underfloor heating with wooden floors?

Yes, but you should check with your flooring manufacturer about the maximum temperature it can withstand to avoid it warping or shrinking. Stone, tile or concrete floors are best, but other forms of flooring do work well too.