Underfloor heating promises a warmer, clutter-free home without radiators along the walls — but the decision between wet and electric systems, and whether UFH is genuinely cost-effective, depends heavily on how you use the space, what heat source you have, and what the floor construction is.
For a typical UK kitchen-diner of 25 m², electric mat UFH costs roughly £1,200–£2,500 installed, while a wet system serving the same zone from an existing combi boiler costs £2,500–£4,500. Neither figure tells the whole story without running costs, so this guide covers both.
Wet vs Electric Underfloor Heating
The most important decision is which system type is appropriate for your situation.
Electric underfloor heating
Electric UFH uses resistance heating cables or pre-made mats laid beneath the floor finish. Installation is relatively simple — there is no pipework, no manifold, and no need to connect to the boiler circuit. A qualified electrician (Part P notified work) connects the mat to its thermostat and the consumer unit.
Best suited to:
- Bathrooms, ensuites, and small tiled areas where you want a comfort heat boost
- Retrofits where disruption to screed or joists must be minimised
- Properties on heat pumps or all-electric tariffs where the running cost gap with wet UFH narrows
Limitations:
- High running cost at the current UK electricity rate of approximately £0.25–0.28/kWh (June 2026 price cap)
- Not efficient as the sole heat source for large open-plan areas
- Only effective as primary heat in well-insulated rooms (U-value 0.30 W/m²K or better)
Wet (hydronic) underfloor heating
Wet UFH circulates warm water — heated to 35–55°C rather than the 70–80°C needed for radiators — through 16 mm or 20 mm polyethylene pipes in a screed floor or stapled to a timber subfloor. A manifold distributes flow between zones, each with its own thermostat.
Best suited to:
- Whole-house systems in new builds or major renovations where floors are open
- Ground-floor extensions where a new screed is being poured
- Properties with heat pumps: heat pumps operate at maximum efficiency (COP 3.0–4.5) when producing 35–45°C flow temperature, which is precisely what wet UFH needs
Limitations:
- Higher installation cost and significant disruption: adding UFH to existing timber floors means either a liquid screed overlay (40–65 mm added floor level) or cutting into joists
- Slower response times (1–4 hours from cold) make it better suited to systems left running continuously at a setback temperature rather than switched on-demand
- Requires regular manifold maintenance — balancing, checking actuators, and bleeding circuits every 2–3 years
Installation Costs
Electric UFH installation costs
| Application | Low | Typical | High |
|---|---|---|---|
| Bathroom (4–6 m²), mat and thermostat | £350 | £600 | £900 |
| Kitchen (15–20 m²), mat and thermostat | £900 | £1,500 | £2,200 |
| Open-plan ground floor (40–60 m²) | £2,500 | £4,200 | £6,500 |
| Per m² (supply and fit) | £50 | £85 | £150 |
Thermostats with Wi-Fi scheduling (Heatmiser neoStat, Honeywell T6R) add £80–£180 per zone but pay back quickly in reduced running hours.
Wet UFH installation costs
Wet system pricing varies considerably based on floor construction and whether a screed is being poured regardless (e.g. in an extension).
| Scenario | Low | Typical | High |
|---|---|---|---|
| Extension or new build (per m², into screed) | £85 | £130 | £200 |
| Retrofit to existing timber floor (per m², overlay plates) | £120 | £165 | £240 |
| Manifold, pump, actuators (2–4 zones) | £600 | £950 | £1,600 |
| Connection to existing boiler | £400 | £700 | £1,200 |
| Whole house (150 m² new build, ground floor + 1st floor) | £14,000 | £22,000 | £35,000 |
Where wet UFH is added to an existing property’s timber floor using aluminium diffuser plates rather than a screed, the floor level rises by only 18–22 mm — manageable in most cases. Liquid anhydrite screed on an extension is typically included in the extension cost and adds only £15–£25/m² as a marginal cost for the UFH pipe within it.
Running Costs: Wet vs Electric
This is where the comparison becomes critical.
Electric UFH consumes roughly 100–150 W/m² at full load. At £0.27/kWh, a 20 m² bathroom-to-open-plan area running 6 hours/day would cost:
- 20 m² × 0.12 kW/m² × 6 h = 14.4 kWh/day × £0.27 = £3.89/day, or roughly £117/month in peak winter
In practice, thermostats limit this significantly — a tiled bathroom mat set to switch off at 22°C won’t run continuously — but electric UFH as primary whole-house heating quickly becomes expensive.
Wet UFH with a gas combi boiler at 90% efficiency, heating to 45°C flow temperature, uses roughly 60–80 W/m² of heat input. At a gas rate of £0.06/kWh:
- 20 m² × 0.07 kW/m² × 6 h ÷ 0.90 efficiency = 9.3 kWh/day × £0.06 = £0.56/day
Wet UFH with an air source heat pump (COP 3.5 at 45°C) brings electricity consumption down to roughly 0.02–0.03 kW/m² of electricity for the same heat output — making it the cheapest option per unit of heat delivered, though the heat pump installation itself costs £8,000–£16,000.
| System | Approx. running cost per m² per heating season (6 months) |
|---|---|
| Electric UFH (thermostatic, part-time use) | £18–£45/m² |
| Wet UFH + gas boiler | £3–£7/m² |
| Wet UFH + air source heat pump | £2–£5/m² |
Best Use Cases
UFH is unambiguously the right choice when:
- You are pouring a new screed in an extension — the pipe adds minimal cost and the system is virtually free at that point
- You are installing an air source heat pump and want to maximise efficiency — wet UFH at 35–45°C is the ideal pairing, and the Boiler Upgrade Scheme (£7,500 grant as of 2026) can offset heat pump costs
- You want to heat a tiled floor in a bathroom or kitchen as a comfort supplement — electric mats are cost-effective and simple here
UFH is harder to justify when:
- You are retrofitting to a finished house with existing radiators and no other reason to open floors — unless it is part of a broader renovation
- You have poor insulation (walls U-value above 0.45 W/m²K, loft below 270 mm mineral wool) — sort the building fabric first
- The property is a rental let where you want quick, on-demand heat — UFH’s slow thermal mass works against intermittent occupancy
Building Regulations and Planning
Electric UFH is notifiable under Part P of Building Regulations if it involves a new circuit from the consumer unit or work in a bathroom (the entire bathroom, not just adjacent circuits). Use a registered electrician (NICEIC, NAPIT) to self-certify, or notify Building Control directly for approximately £100–£200.
Wet UFH connected to a boiler is unregulated as a heating circuit change, but if you are also installing a new heat pump this requires MCS certification from the heat pump installer (required to claim the Boiler Upgrade Scheme grant). The heat pump installation itself must comply with Part L (energy efficiency) of Building Regulations.
There is no planning permission requirement for UFH in England, Scotland, or Wales under any normal circumstances.
Timescales
| Stage | Duration |
|---|---|
| Electric mat installation (bathroom) | Half a day |
| Electric mat installation (ground floor) | 1–2 days |
| Wet UFH manifold and pipework (extension, 50 m²) | 2–3 days (then wait for screed) |
| Anhydrite screed cure time before floor finish | 28 days minimum (28°C ambient) |
| Commissioning and balancing | Half a day |
The screed curing period is the critical path in any wet UFH project — you cannot lay tiles, LVT, or engineered wood until the screed moisture content falls below 75% RH (checked with a calibrated hygrometer).
Is It Worth It?
For a new extension with a new screed, wet UFH is almost always worth adding — the marginal cost is low and it pairs perfectly with a future heat pump. For a bathroom upgrade, electric mats deliver comfort for a reasonable upfront cost. For whole-house retrofit in an older property with joists and radiators, the disruption cost typically means the payback period is 12–20 years at current energy prices.
If you are planning a heat pump installation under the Boiler Upgrade Scheme, designing the ground floor around wet UFH from the outset is strongly recommended — it is the single most effective way to keep the heat pump’s flow temperature, and therefore its running costs, as low as possible.
