Short answer: Electric underfloor heating can be fitted in a bathroom, including under the floor near the bath or shower, if the circuit has 30mA RCD protection and the heating cable has a metal sheath, metal enclosure or fine mesh grid connected to the circuit's protective conductor, as BS 7671 Section 701 requires. Put the thermostat outside zones 1 and 2, ideally outside the room, and run the floor probe in conduit. In England, a new circuit, or any addition or alteration to a circuit within 0.6m of the bath or shower tray up to 2.25m high, is notifiable under Part P, so use a registered electrician or tell building control.
Bathrooms are one of the most popular places for electric underfloor heating, and one of the most tightly regulated. Water and electricity together raise the risk of shock, so BS 7671 treats a room with a bath or shower as a special location with extra rules.
This guide explains the bathroom zones, the RCD and earthing rules for heating cables, where the thermostat can go, when the work is notifiable, and gives a priced worked example. For the wider rules on electric floor heating, see our guide to BS EN 1264 and BS 7671 in plain English.
What are the bathroom zones?
BS 7671 Section 701 divides a bathroom into zones based on the bath or shower, and sets what can go in each one. The IET explains the dimensions like this:
| Zone | Where it is |
|---|---|
| Zone 0 | Inside the bath or shower tray |
| Zone 1 | Above the bath or tray, up to 2.25m |
| Zone 1, no tray | Within 1.2m of the shower outlet |
| Zone 2 | 0.6m beyond zone 1, same height |
| Outside zones | Rest of the room |
The height of zones 1 and 2 is 2.25m above the finished floor, or the height of the highest fixed shower head or outlet if that is higher. Electrical equipment in zones 1 and 2 must be at least IPX4, or IPX5 where water jets are used for cleaning.
Part P uses a similar space for its own purpose. Approved Document P defines the special location as the space within 0.6m of the edge of the bath or shower tray, from the floor up to 2.25m or the shower head if higher. With no tray, it is 1.2m from the centre of the shower head.
Can electric underfloor heating go under the bath or shower area?
The floor near the bath or shower can be heated, but the heating cable or element must be earthed in a specific way. IET guidance on Section 701 says that for electric floor heating in a bathroom, the heating cables or thin flexible heating elements must have a metal sheath, a metal enclosure or a fine mesh metallic grid, connected to the protective conductor of the supply circuit. That isn't needed if the system runs on SELV, safety extra-low voltage. Protection by electrical separation is not allowed for floor heating.
In practice:
- Choose a cable or mat with an earthed metal screen or braid. Our loose heating cable is twin core with an earth screen. Check the data for any mat before you buy.
- Don't lay heating under the bath, shower tray, toilet or fixed units. The heat is trapped and wasted. Our mat sizing guide is to measure the free floor area only.
- Keep heating cables away from where the toilet and basin will be fixed to the floor. Section 753 requires areas where screws or nails may be driven to be kept free of heating.
Does bathroom underfloor heating need an RCD?
Yes. Regulation 701.411.3.3 requires additional protection by one or more RCDs of 30mA or less for all low voltage circuits serving the location. Section 753 also requires 30mA RCD protection for floor heating units. So a bathroom heating mat must be on a 30mA RCD or RCBO.
The RCD rule is separate from supplementary bonding. Regulation 701.415.2 allows supplementary bonding in the bathroom to be left out only if all of these are true:
- All final circuits in the location meet the automatic disconnection requirements.
- All final circuits have 30mA RCD protection.
- All extraneous conductive parts, such as metal pipes entering the room, are connected to the main protective bonding.
Your electrician decides whether bonding is needed after testing the installation.
Where should the bathroom UFH thermostat go?
Put the thermostat outside zones 1 and 2. IET guidance says accessories such as switches may be installed beyond zone 2, and anything in zones 1 and 2 must be at least IPX4. Most wall thermostats are not rated for the zones, so the simplest answer is to fit the thermostat just outside the bathroom door.
- Use a floor-sensing thermostat. An electric floor thermostat such as the Heatmiser neoStat-e or Slimline-E switches up to 16A and comes with a floor sensor.
- Run the probe in conduit between two cable runs, so it can be replaced without lifting tiles.
- Don't use a receiver with no floor limit. Heatmiser state that its RF-Switch 16A has no floor limiting sensor function, so it is not designed for electric underfloor heating.
Section 753 also requires the floor surface temperature to be limited where skin or footwear can touch it. The floor sensor is how you set that limit. Our guide to electric UFH thermostats and 16A loads covers thermostat choice.
Is bathroom underfloor heating notifiable under Part P?
Usually, yes. In England, electrical work in a home is notifiable if it is a new circuit, a replacement consumer unit, or an addition or alteration to existing circuits in a special location. Approved Document P says that within the special location, minor additions and alterations are notifiable, as well as new circuits.
| How the mat is supplied | Notifiable? |
|---|---|
| New circuit from consumer unit | Yes |
| Spur, work within 0.6m of bath | Yes |
| Spur, all work outside special location | No, but must meet BS 7671 |
Most bathroom mats run close to the bath or shower, so treat the job as notifiable unless your electrician confirms otherwise. Notifiable work can be self-certified by an electrician registered with a competent person scheme, certified by a registered third party appointed before work starts, or approved by your building control body.
Worked example: a 2.4m x 2.0m bathroom
A family bathroom of 2.4m x 2.0m has a 1.7m x 0.7m bath, a toilet and a pedestal basin. The floor is tiled over an existing concrete slab.
- Room area: 2.4 x 2.0 = 4.8m².
- Take off the bath: 1.7 x 0.7 = 1.19m². Allow about 0.4m² for the toilet and basin and the gaps around them. Free floor area is about 3.2m².
- Choose the mat closest to the free area without going over it: a 3.0m² mat.
- At 150W/m², the mat is 450W. Current is 450 ÷ 230 = about 2A, well within a 16A thermostat.
- Supply it from a circuit with 30mA RCD protection, with the thermostat outside the bathroom door.
| Item | Price inc VAT |
|---|---|
| Heating mat 150W/m², 3.0m² | £77 |
| Heatmiser neoStat-e (floor sensor included) | £83 |
| Total before boards and adhesive | £160 |
Prices October 2026. Add insulated tile backer board to cut heat loss into the slab, and the electrician's labour. On a timber floor, add an uncoupling membrane under the tiles. If the room is an awkward shape, loose cable laid in an uncoupling membrane can cover more of the floor than a mat.
What paperwork should I get?
You should get an electrical installation certificate to BS 7671, plus a Building Regulations compliance certificate if the electrician is registered with a competent person scheme. IET guidance on Section 753 also requires a plan of the heating installation, fixed at or near the distribution board, showing details such as the heating unit type, rated power, layout, cold resistance, insulation resistance and the protective device ratings.
Keep the mat's packaging label and take photos of the layout before tiling. They show where the cable runs if anyone needs to drill later.
Products for this job
Prices include VAT, October 2026.
- MaxHeatUFH Electric Heating Mat 150W/m²: from £41 (1.0m²)
- MaxHeatUFH Electric Heating Mat 100W/m², for en-suites: from £39
- MaxHeatUFH Loose Heating Cable, twin core with earth screen: from £14
- Heatmiser neoStat-e: £83
- Heatmiser Slimline-E: £56
- Uncoupling Membrane, 1m x 5m: £57
- 10K Floor Probe (3m), spare: £13
- All electric underfloor heating
Related guides: How to install an electric underfloor heating mat and Water vs electric underfloor heating.
Heating a bathroom or a whole floor? Design it free with MaxHeatUFH ProLoop. Add your rooms and floor type, and get a layout and full kit list with prices, for electric or water underfloor heating. Start your design
Frequently asked questions
Can you put electric underfloor heating in a bathroom?
Yes. It needs 30mA RCD protection, a heating cable with an earthed metal sheath, enclosure or grid unless it runs on SELV, and the thermostat outside zones 1 and 2. The final connection should be made by a qualified electrician.
Can underfloor heating go in a shower area?
The floor around a shower can be heated if the cable meets the Section 701 earthing rule. Don't lay heating under the shower tray itself. In a wet room with no tray, check the build-up and waterproofing with the tanking and heating makers.
Can the thermostat go inside the bathroom?
Only outside zones 1 and 2, and only if it is suitable for the conditions. Most installers fit it just outside the bathroom door, which avoids the question.
Does a bathroom heating mat need its own circuit?
Not always. A small mat can often be supplied from an existing circuit, if the circuit has capacity and 30mA RCD protection. A new circuit is always notifiable under Part P.
Do I need building control for bathroom underfloor heating?
Usually, yes. Work on circuits in the space around the bath or shower, or a new circuit, is notifiable. A registered electrician can self-certify it, otherwise you need building control approval.
Can I tile straight over a heating mat in a bathroom?
Yes. The mat sits in the tile adhesive bed, about 3 to 4mm thick. On timber or new screed, use an uncoupling membrane to protect the tiles from movement.
Sources: Approved Document P (gov.uk), IET Wiring Matters: Section 701 locations containing a bath or shower, IET Wiring Matters: floor and ceiling heating, IET EngX: RCD protection in bathrooms, IET: Amendment 4 updates