Underfloor heating installation FAQ: costs, specs & grants

In 2026, supplying and installing wet (hydronic) underfloor heating in an Irish new build or extension costs €40 to €65 per m² for the pipework, manifold and room thermostats, or €65 to €95 per m² complete with 50mm pumped liquid screed. Low-profile 15mm–18mm retrofit overlay systems cost €85 to €125 per m², and electric heating mats for bathrooms cost €45 to €75 per m².

Yes. Low-profile retrofit overlay panels (15mm to 18mm total build-up) bond directly on top of your existing concrete slab or floor tiles and carry 12mm oxygen-barrier pipe in a thin fibre-reinforced levelling compound. Alternatively, if you have a sound 60mm+ sand-and-cement screed, dust-free diamond milling cuts 16mm pipe channels flush into the top of the existing slab with 0mm added floor height.

Hydronic underfloor heating paired with an air-to-water heat pump in Ireland is designed for a 35°C flow temperature (and 28°C–30°C return) at -3°C outdoor temperature. Running at 35°C instead of 50°C–55°C radiator temperatures boosts heat pump seasonal efficiency (SCOP) above 4.0 and cuts winter running costs to roughly 8.5c–9.8c per kWh of heat.

While SEAI does not grant-aid underfloor heating on a standalone fossil boiler, homeowners upgrading a pre-2021 property to an air-to-water heat pump can claim up to €14,500 under the SEAI Heat Pump System Grant (€11,500 for apartments), which includes up to €2,000 (€1,000 for apartments) specifically towards installing underfloor heating.

Wet hydronic pipework is the right choice for whole ground floors, extensions and open-plan renovations over 15 m² because its running cost on a heat pump or condensing boiler is three to four times lower than direct electricity. Electric heating mats (150W–200W/m²) are ideal for single bathrooms, en-suites and small upstairs wetrooms under 10 m² where 3.5mm–5mm thickness and low upfront installation cost matter most.

With a 50mm calcium-sulphate (anhydrite) or flowing cementitious liquid screed, you can walk on the floor after 24–48 hours and start the gentle EN 1264-4 commissioning heat-up cycle at 20°C–25°C after 7 days (compared with waiting 21–28 days on traditional hand-laid sand-and-cement screed).

For an air-to-water heat pump running at a 35°C flow temperature, 16mm pipe is normally clipped at 150mm centres across living areas and 100mm centres in bathrooms or high-heat-loss sunrooms. Individual 16mm loops are kept below 100 linear metres (roughly 14–15 m² per port), while 12mm low-profile retrofit pipe is clipped at 100mm–125mm centres with loops capped at 60–75 linear metres.

When a heat pump feeds an open-plan ground-floor underfloor heating manifold directly (and at least one or two zones remain open or weather-compensated), no blending mixing valve is needed because the heat pump already produces 30°C–38°C water. Mixing valves are only fitted when a 65°C–75°C gas or oil boiler feeds the manifold.

In a new build or full ground-floor dig-out, the insulation (120mm–150mm PIR) and screed (50mm liquid screed or 65mm–75mm sand-and-cement) are already part of the structural floor build-up, so the heating pipes add 0mm of extra height. In an existing room where you keep the concrete slab intact, a low-profile wet overlay system adds just 15mm to 18mm before tiles or wood, and an electric decoupling mat adds 3.5mm to 5.5mm.

Yes — dual-temperature hybrid systems are standard in Irish extensions and two-storey refurbishments. On a condensing gas or oil boiler, the upstairs radiators run at 60°C–70°C on Zone 1 while a thermostatic pump-and-mixing pack steps the downstairs manifold down to 40°C–45°C on Zone 2. On a heat pump, low-temperature aluminium or double-panel K2/K3 radiators upstairs run alongside the downstairs floor at 35°C–42°C.

For a 60 m² to 100 m² ground floor or extension, laying the perimeter strip, foil vapour membrane, 16mm pipe loops, manifold, and air/water pressure test takes 1 to 2 working days before the screed team pours. Low-profile retrofit overlay boards across a 40 m² kitchen-diner take 1 to 2 days including self-levelling compound, and a bathroom electric heating mat takes half a day before tiling.

Every hydronic loop is flushed clean of air, filled with water (or compressed air in freezing weather), and pressure-tested to 6 bar (twice normal operating pressure) in accordance with EN 1264-4. The manifold pressure gauge remains locked at 3 to 6 bar throughout the liquid screed pour so any accidental site damage is spotted immediately.

In well-insulated Irish new builds and extensions running on an air-to-water heat pump (35°C flow), 16mm pipes are clipped at 150mm centres across living rooms, kitchens and bedrooms, and tightened to 100mm centres in bathrooms, wetrooms and heavily glazed sunrooms.

To satisfy Irish Building Regulations Part L (and SEAI's 0.15 W/m²K floor U-value benchmark for heated floor refurbishments), ground-floor slabs typically use 120mm to 150mm of foil-faced PIR insulation board plus a 25mm–50mm perimeter upstand strip around external walls to stop thermal bridging.

No — the screed must cure, complete its controlled EN 1264-4 commissioning heat-up cycle, cool down, and pass a moisture test (<75% RH on a hygrometer or <0.5% CM on anhydrite screed) before any adhesive or floor covering goes down.

5-layer cross-linked polyethylene (PE-Xa) and raised-temperature polyethylene (PE-RT) oxygen-barrier pipes manufactured to DIN 4726 have a service life of 50+ years encased inside the floor screed, with no moving parts under the floor. The above-ground manifold actuators and circulation pump are easily serviced inside the manifold cupboard.

Yes — under Safe Electric rules in Ireland, wiring a 230V electric underfloor heating mat into a 30mA RCD-protected circuit (especially inside bathroom zones) is Restricted Electrical Work and must be tested and certified by a Registered Electrical Contractor.

Your enquiry is sent directly to one vetted underfloor heating installer covering your county. They call you to review your room dimensions, subfloor build-up and heat source, and provide a written supply-and-install quote with no obligation.