Electric Underfloor Heating: Complete UK Guide
Electric underfloor heating uses resistance cables or mats beneath floor finish to provide efficient, zone-controlled heating in UK homes.
Electric underfloor heating uses thin resistance cables (150W per m²) installed under tile, laminate or engineered wood. Costs £75–120 per m² to install in UK, runs at 10–15p per kWh electricity. Best for bathrooms, kitchens and conservatories. Not cost-effective as primary heating for whole house.
What is electric underfloor heating?
Electric underfloor heating (electric UFH) warms rooms by running electrical resistance cables beneath the floor finish. When current flows through the cables, they heat up and radiate warmth upward through the floor surface.
Two main types:
- Heating mats: Cables pre-spaced and fixed to mesh backing, easy to lay, £40–75 per m²
- Loose-wire systems: Individual cables you space manually, more flexible layout for awkward rooms, £30–60 per m²
Both plug into a wall-mounted thermostat that controls floor temperature. Most UK installations use 150W per m² power rating (suitable for bathrooms and supplementary heating).
How electric UFH works
The heating cable is a twin-core insulated resistance wire. When powered, electrical resistance generates heat. The cable is embedded in tile adhesive (under ceramic/porcelain) or self-levelling compound (under laminate/engineered wood).
Heat conducts through the floor material and radiates into the room. Floor surface reaches 25–28°C (safe underfoot, warm to touch).
A floor probe monitors temperature and signals the thermostat to cycle power on/off to maintain set temperature. Most thermostats allow programming: heat bathroom 06:00–08:00 for morning routine, off during day, on again 18:00–22:00.
Electric vs wet underfloor heating
| Feature | Electric UFH | Wet UFH (water pipes) |
|---|---|---|
| Installation cost | £75–120 per m² | £80–150 per m² + manifold + pump |
| Running cost | 10–15p per kWh (electricity) | 3–5p per kWh (gas boiler) or 2–4p (heat pump) |
| Heats up time | 30–60 minutes | 2–3 hours |
| Retrofit ease | Easy (low build-up height) | Hard (needs 50mm+ screed or battens) |
| Whole-house heating | Not cost-effective | Efficient primary heating |
| Lifespan | 25–30 years | 40–50 years |
Electric UFH suits single rooms (bathroom, kitchen). Wet UFH suits whole-house installations or new builds where you're laying screed anyway.
Installation under different floor types
Under tile (ceramic/porcelain)
Most common installation. Steps:
- Ensure subfloor is level, dry and insulated (use 6mm insulation board if over uninsulated concrete)
- Roll out heating mat or fix loose wire to subfloor using adhesive or fixing tape
- Test cable resistance (must match manufacturer spec before proceeding)
- Spread flexible tile adhesive over cables with notched trowel
- Lay tiles, ensuring full adhesive coverage (voids cause hot spots)
- Grout tiles after 24 hours
- Wait 7 days before switching on heating (adhesive must fully cure)
Build-up height: 10–15mm (insulation + cable + adhesive + tile).
Under laminate or engineered wood
Requires self-levelling compound to encapsulate cables:
- Lay insulation board (6–10mm XPS foam with foil facing)
- Fix heating cables to insulation
- Pour self-levelling compound over cables (15–20mm depth)
- Allow 24 hours to set
- Lay laminate/engineered wood on top (floating installation with thin underlay)
Build-up height: 30–40mm. Check door clearances before starting.
Laminate and engineered wood must be UFH-compatible (thermal resistance under 1.5 tog). Thick or dense floors insulate too much, reducing heating efficiency.
Under carpet
Possible but inefficient. Carpet and underlay insulate heavily (thermal resistance 1.5–2.5 tog), so heat struggles to reach the room. You'll use more electricity for less warmth. If you must heat under carpet, use low-tog underlay and specify high-output cables (200W per m²).
Running costs
UK electricity averages 28p per kWh (2026). Electric UFH typically draws 150W per m², so:
10m² bathroom (typical UK):
- Power draw: 1.5kW
- Cost per hour: £0.42
- 3 hours daily: £1.26 per day = £460 per year
Thermostat cycles on/off to maintain temperature, so actual runtime is 40–60% of total "on" time. Real annual cost for that bathroom: £180–275.
Compare to radiator: a 1kW towel radiator running the same schedule costs similar (£180–260 per year) but heats the room less evenly.
UFH is not cheap to run as primary heating for large areas. A 40m² open-plan kitchen/diner would cost £700–1,050 per year to heat electrically. Gas or heat-pump wet UFH costs £150–300 for the same room.
Thermostat options
Basic on/off thermostat: £40–70. Manual dial, no programming.
Programmable thermostat: £80–150. Set different temperatures for different times (e.g. warm mornings, off during work day). Most include floor probe to prevent overheating.
Smart thermostat: £120–250. Wi-Fi enabled, control from phone, learns your schedule. Examples: Heatmiser NeoStat, Warmup 4iE, Honeywell Evohome.
All thermostats need a floor probe (temperature sensor embedded in the floor near the cables). Without it, the thermostat guesses based on air temperature, which leads to overheating or underheating.
Installation cost UK
DIY-able if you're confident with electrics, but final connection to mains must be done by qualified electrician (Part P Building Regulations).
Material costs:
- Heating mat (150W/m²): £40–75 per m²
- Loose-wire system: £30–60 per m²
- Insulation board: £8–15 per m²
- Thermostat: £80–250
Labour (if hiring electrician for full install): £30–50 per m².
Total installed cost for a 5m² bathroom: £400–750.
Compatible floor finishes
Best to worst for heat transfer:
- Ceramic/porcelain tile: Excellent thermal conductivity, retains heat well
- Natural stone: Very good, heavier so stores more heat
- Engineered wood: Good if under 1.5 tog total resistance
- LVT (luxury vinyl tile): Good, check manufacturer confirms UFH compatibility
- Laminate: Acceptable if UFH-rated and used with thin underlay
- Carpet: Poor, too much insulation (not recommended)
Lifespan and warranty
Quality electric UFH cables last 25–35 years. The cable is sealed and has no moving parts, so failure is rare if installed correctly.
Most failures happen during installation (cable nicked by trowel, over-tensioned during fixing). That's why testing resistance before and after laying adhesive is critical.
Manufacturers offer 10–25 year warranties. Warmup and Prowarm give lifetime warranties on some cable products.
If a cable does fail, you can't easily repair it (it's embedded in adhesive or screed). You'd need to lift the floor finish, locate the break, and replace the damaged section. In practice, most people just install a radiator instead if UFH fails after warranty expires.
Building Regulations and wiring
Electric UFH is notifiable under Part P (electrical safety). Either:
- Hire a registered electrician who self-certifies the work
- DIY the cable laying, but notify Building Control and pay for inspection (£150–300)
The heating cable itself runs at low voltage (typically 230V AC). The thermostat and floor probe are also 230V. Final connection must be on a dedicated circuit with RCD protection.
Best uses for electric UFH
Electric underfloor heating excels in:
- Bathrooms: Warm floor after shower, prevents cold tile shock, zone heating
- Kitchens: Comfortable to stand on while cooking, good under tile
- Conservatories: Adds heating without bulky radiators, quick warm-up
- En-suites: Small area so running cost is low
Not ideal for:
- Whole-house primary heating (too expensive to run on electricity)
- Poorly insulated rooms (heat loss makes it inefficient)
- Carpeted rooms (heat doesn't reach the room effectively)