Wet Underfloor Heating: UK Installation & Costs
Wet underfloor heating circulates warm water through pipes embedded in floor screed, powered by gas boiler or heat pump.
Wet UFH uses PE-X plastic pipes in floor screed, connected to boiler or heat pump via manifold. Costs £80–150 per m² installed plus £800–1,500 for manifold/pump. Runs at 3–5p per kWh (gas) or 2–4p per kWh (heat pump), much cheaper than electric UFH (10–15p per kWh).
How wet UFH works
Hot water from boiler or heat pump flows through 16mm plastic pipes laid in loops across the floor. Flow temperature: 35–45°C (lower than radiators which use 60–70°C). Pipes are spaced 150–200mm apart, embedded in 50–75mm screed.
A manifold controls each zone (living room, kitchen, etc.). Each zone has its own thermostat. Pump circulates water through the system.
Installation methods
Screed system: Lay insulation boards, clip pipes to boards, pour screed over pipes. Cheapest method, best heat distribution. Takes 3–4 weeks (screed must cure before floor finish). Adds 50–80mm floor height.
Dry board system: Grooved boards with pre-cut channels for pipes. No screed needed. Adds only 18–25mm floor height. Faster (ready for floor finish in 2 days) but costs more (£140–220 per m²).
Cost breakdown UK
Materials for 40m² ground floor:
- Pipes + insulation: £1,200–1,800
- Manifold + pump + mixing valve: £800–1,500
- Screed: £600–1,400
- Labour: £1,600–2,800
- Total: £4,200–7,500
Running cost
40m² living space, 8 hours daily heating:
Gas boiler (7p per kWh): £220–330 per year
Heat pump (28p electricity, COP 3.5): £220–330 per year
Compare to electric UFH: £840–1,250 per year for same space.
Retrofit vs new build
Wet UFH is easier and cheaper in new builds (screed floor anyway). Retrofit costs more due to floor height increase or need to lift existing floors.