Underfloor Heating in a Bathroom: Electric vs Wet, Costs and Fitting

In short: Electric underfloor heating is the right choice for almost every existing bathroom: it adds little to the floor height, MyJobQuote puts a 4m² en-suite at £240 to £300 to install (October 2026), and Which? puts the running cost of a 4.5m² bathroom at about 17.7p an hour (May 2026). Wet underfloor heating is cheaper to run but costs more to fit and needs a deeper floor, so it suits a new floor or a whole-house system. It works best under tile and stone, needs an insulation board and a floor probe, and a new circuit for it is notifiable under Part P. In a well-insulated room it can be the only heat source; in most older bathrooms Barbers Bathrooms & Kitchens keeps a heated towel rail as well.

01 Is underfloor heating a good idea in a bathroom?

Yes. A bathroom is the room where underfloor heating earns its keep most clearly: you stand on the floor barefoot, the floor gets wet every day, and in a small room there is rarely a good wall left for a radiator once the bath, shower, basin and WC are in. A warm tiled floor dries quickly after a shower, which cuts down the standing water that makes floors slippery and the lingering damp that feeds mould.

At Barbers Bathrooms & Kitchens we fit bathroom underfloor heating as part of a full bathroom installation, with our own tilers, plumbers and electrician on the job, so the heating, the floor preparation and the tiling are planned together rather than handed between firms.

02 Electric or wet underfloor heating: which is best for a bathroom?

For a single bathroom in an existing house, electric underfloor heating is almost always the better underfloor heating system. An electric system is a heating mat or loose cable bedded in the tile adhesive, wired to a thermostat. A wet (water) system is a loop of PEX pipe in screed or a routed panel, fed with warm water from the boiler or a heat pump through a manifold. Wet underfloor heating is cheaper to run per unit of heat, but it costs far more to fit, adds much more to the floor depth and needs plumbing back to the heating system, so it makes sense in an extension, a new build or a whole floor rather than one bathroom.

All costs in this table are published third-party market figures, not our prices. We quote each bathroom in writing after a survey.

03 How much does bathroom underfloor heating cost to install?

Electric underfloor heating for a bathroom typically costs £40 to £90 per m² supplied and fitted, according to MyJobQuote's underfloor heating cost guide (last updated October 2026), which puts a 4m² en-suite at £240 to £300. The same guide gives £100 to £190 per m² for wet underfloor heating, or £600 to £720 for the same en-suite. Rated People (prices stated accurate as of 2026) gives £600 to £850 for electric underfloor heating in a 10m² bathroom and £1,350 to £1,850 for a wet system.

MyJobQuote also notes that small rooms such as en-suites and cloakrooms cost more per square metre, because the thermostat, the electrician's connection and the testing cost the same whatever the size of the mat. Added during a renovation, the floor is already up and the electrician is already on site, so the heating adds far less than it would as a separate job later. For the wider budget, see how much a bathroom renovation costs.

04 How much does electric underfloor heating cost to run in a bathroom?

Electric underfloor heating in a 4.5m² bathroom costs about 17.7p an hour to run while it is drawing power, according to Which? (May 2026). Which? bases that on a standard system using around 150W per m², and on the 27.69p per kWh price cap for October to December 2025. MyJobQuote (October 2026) puts a 4m² electric en-suite at about £50 to £90 a year, against £25 to £50 a year for a wet system on a gas boiler.

You can work out your own figure: multiply the heated area by the mat's output, then by the hours it actually draws power and your unit rate. The hours are what people overestimate. A bathroom floor on a thermostat cycles on and off once it is up to temperature, and most households only need it warm for an hour or two in the morning and evening in winter.

05 How long does bathroom underfloor heating take to warm up?

Electric underfloor heating over an insulation board warms a tiled floor in roughly half an hour; without the board it can take well over an hour and a half. That is what Warmup's insulation board test data (data sheet dated September 2022) shows for a 150W/m² mat over a 75mm screed: bringing the floor from 18°C to 27°C took over 100 minutes with no insulation, and around 30 minutes with a 6mm or 10mm board.

The board works because it stops the heat soaking down into the concrete or the void below, so it goes up into the tile instead. Wet underfloor heating heats up more slowly than electric, and also holds its heat for longer after it switches off. Either way, a programmable or smart thermostat set to come on before you get up means the floor is already warm when you need it.

06 Can underfloor heating be the only heat source in a bathroom?

Sometimes, and it comes down to arithmetic rather than opinion. A standard electric mat gives around 150W per m² of heated floor, the figure Which? uses, and Homebuilding & Renovating notes outputs running from about 50W/m² to over 200W/m². Crucially, that is heated floor, not floor area: you cannot lay it under the bath, the shower tray, the WC pan or a vanity unit, so a 6m² bathroom often has only 3m² to 3.5m² of usable heated area, around 500W at 150W/m².

Whether that heats the room depends on the room. A small, modern, well-insulated en-suite will be comfortable on it. A bathroom with a solid external wall, a single-glazed window and no insulation under the floor will not, and you end up with warm feet in a cold room.

Our default recommendation is underfloor heating plus a heated towel rail. The towel rail dries towels, which the floor cannot do, and it keeps the room warm on the coldest morning of the year rather than only in spring.

07 How much does underfloor heating raise the bathroom floor?

An electric heating mat itself adds very little: Homebuilding & Renovating gives less than 10mm for the heater, and Which? (May 2026) puts the wire at 4 to 5mm. The insulation board under it adds more, from 6mm upwards. A wet system is deeper: at least 20mm even for a low-profile retrofit, according to Homebuilding & Renovating (June 2023), and Which? gives around 130mm for a screeded system.

Build-up matters at the door threshold and in a wet room, where the floor has to fall to the drain and stay level with the landing. We measure the finished floor height at survey, including the board, adhesive bed and tile, so the door, the threshold strip and the shower former all line up.

08 Do you need insulation boards under underfloor heating?

Yes, in almost every bathroom. The insulation board stops the heat going downwards into the concrete floor or the void between the joists, so the floor warms faster and costs less to run, as the Warmup test data above shows. It is the part people are tempted to leave out to save depth and money, and it is the wrong thing to leave out.

On a concrete floor the board is bedded in flexible adhesive. On a suspended timber floor we first make the floor rigid with an overlay of exterior-grade plywood screwed at close centres, then lay a cement-coated insulation board or tile backer board, because a heated tile floor on bouncing boards will crack. Where a floor still has some movement, a decoupling mat between the heating layer and the tile is an option.

09 Which floor finishes work with underfloor heating?

Porcelain, ceramic and natural stone tiles work best with bathroom underfloor heating, because they conduct heat well; MyJobQuote says the same. LVT and vinyl work too, provided the floor temperature is held below the maximum the flooring maker sets, which is why a floor probe matters. Engineered wood can work where its manufacturer permits it, but it is a poor choice in a bathroom for other reasons.

• Porcelain and ceramic tile: the best match. Thin, dense and quick to warm.
• Natural stone: works well and holds heat, but is slower to warm than thin porcelain.
• LVT and sheet vinyl: suitable if the product is rated for underfloor heating and a floor probe limits the temperature.
• Thick carpet and underlay: not suitable. It insulates the floor from the heat, and carpet does not belong in a bathroom anyway.
• Solid timber: avoid. It moves with heat and humidity.

For a full comparison of floor finishes, see our guide to the best bathroom flooring in the UK.

10 What thermostat does bathroom underfloor heating need?

Bathroom underfloor heating needs a thermostat with a floor probe. The probe is a sensor that sits in a conduit between two runs of heating cable and tells the thermostat what the floor is actually doing, so the controller can hold a comfortable floor temperature and never overheat the tile adhesive or an LVT floor. A thermostat that only senses air temperature cannot do that.

A programmable or smart thermostat lets you set the floor to warm before you get up and switch off once the house is empty, which is where most of the running-cost saving comes from. The thermostat goes outside the bathroom or in a position outside the bath and shower zones.

11 Does electric underfloor heating need building regulations approval (Part P)?

Yes, if it goes on a new circuit, and in a bathroom it almost always does. Under Approved Document P on GOV.UK, a new circuit is notifiable building work, and bathrooms are special locations where work within the zones around a bath or shower is notifiable too. Notifiable work must be done by an electrician registered with a competent person scheme, who self-certifies it, or notified to building control before it starts.

MyJobQuote and Which? both make the same practical point: the heating mat itself is simple to lay, but a qualified electrician has to connect it to the mains and wire the thermostat. The circuit also needs RCD protection. You should receive the electrical certificate at handover; keep it with the house documents, because a buyer's solicitor will ask for it. Our guide to bathroom building regulations covers the rest.

12 When is underfloor heating fitted during a bathroom renovation?

Underfloor heating goes in after the strip-out and the first-fix electrics, and before the floor is tiled, so in a bathroom renovation it is part of the floor-preparation stage rather than a separate job. Planning it at survey matters, because the thermostat position, the finished floor height and the layout of the bath, tray and WC all decide where the mat can go. This is the order our team follows:

1. Strip out and check the floor. It must be sound, clean, dry and flat, because the mat follows whatever is underneath it. On timber floors we overlay with ply first.
2. First fix electrics: the cold tail and the floor probe conduit are run back to the thermostat position before anything is covered.
3. Insulation boards bonded and fixed down.
4. The mat or cable laid out, kept clear of where the bath, tray, WC and units will sit, and tested with a meter. We record the resistance before, during and after tiling, and photograph the layout so nobody drills through it later.
5. Tiled over in a flexible adhesive, or after a levelling compound where the mat is a loose cable.
6. Left to cure before the heating is switched on. The adhesive's data sheet sets the wait: Palace Chemicals' Extra-Lite Standard Set data sheet, for example, says to allow 28 days before switching the heat on over a heated floor, then raise the temperature gradually through the first week.

Laying the board and the mat usually adds half a day to a day to a bathroom we are already fitting, and no calendar time, because it happens inside the floor-preparation stage. See how long a bathroom renovation takes for the full sequence.

13 Where must underfloor heating not be laid?

• Under the bath, the shower tray, the WC pan or any fixed floor-standing unit. Heat with nowhere to go damages the cable, and heating manufacturers exclude it.
• Anywhere you will later drill or screw into the floor, such as a pedestal fixing or a door stop. Mark and photograph the layout before tiling.
• Into the fall around a wet room drain. The mat stops short of the drain and sits above the tanking membrane, never below it.
• Under thick carpet or solid timber.

14 What are the downsides of underfloor heating in a bathroom?

The main downsides are running cost, floor height and access. Electric underfloor heating costs more per unit of heat than a gas-fired radiator; the floor rises by the depth of the board and mat; and a fault under tiles is harder to reach than a radiator valve. The common problems we see in bathrooms other people have fitted are almost all installation faults rather than product faults: no insulation board, so the floor is slow and expensive; an air-only thermostat that overheats an LVT floor; a cable nicked during tiling and never tested; or the heating switched on before the adhesive had cured, which cracks a new floor. Every one of those is avoided by testing the mat at each stage, fitting a floor probe and waiting the full cure time.

15 Can you fit underfloor heating yourself?

You can lay an electric mat yourself, but you cannot connect it yourself unless you are a registered electrician. Which? says a competent DIYer can lay an electric system, but a qualified electrician is needed to connect it to the mains and fit the thermostat, and in a bathroom that new circuit is notifiable under Part P. The laying is the easy part; the board, the tile bed, the testing and the cure time are what decide whether the floor lasts.

16 Who fits bathroom underfloor heating near Worksop and Creswell?

Barbers Bathrooms & Kitchens, based in Creswell, Derbyshire, fits electric underfloor heating as part of the bathrooms we install across Derbyshire, Nottinghamshire and South Yorkshire. Our tilers lay the boards and the tile; our electrician wires the circuit, and the electrical certificate is handed over at the end; the whole job is run by Dan Barber, Master Joiner and Director (NVQ Level 3 Carpentry and Joinery). If you are looking for bathroom fitters in Worksop, or want the floor tiled to go with it through our wall and floor tiling service, we quote in writing after a survey.