Installing underfloor heating costs €20 to €80 per square metre, depending on the system and the floor covering. Electric underfloor heating is cheaper to install (€20–€40/m²) but more expensive to run. A wet (water-based) underfloor heating system costs more to install (€40–€80/m²) but pays back more quickly when used with a heat pump or boiler. Have everything done by a contractor and you’ll pay €80–€150 per m². In this article you’ll learn how both systems work, what they cost, and which system best suits your situation.
Electric vs. water: which system do you choose?
| | Electric underfloor heating | Wet underfloor heating |
|—|—|—|
| Installation costs (materials) | €20 – €40/m² | €40 – €80/m² |
| Installation time | 4–8 hours per room | 2–4 days (whole house) |
| Can you install it yourself? | Mostly yes | Partly (boiler/heat pump: no) |
| Running costs | €0.30–€0.50/kWh | €0.05–€0.20/kWh (heat pump) |
| Payback period | Not applicable (expensive to run) | 5–15 years |
| Suitable for | Bathroom, toilet | Whole house, new build |
| Warm-up time | 20–30 minutes | 1–3 hours |
Advice:
- Bathroom or toilet: electric — cheaper, easier, works well for small spaces
- Whole house or renovation: wet — higher installation costs but significantly lower running costs
- Rental property or temporary: electric — easier to remove
Electric underfloor heating: how does it work?
Electric underfloor heating consists of a heating cable or mat laid beneath the floor. A thermostat controls the temperature.
Types:
- Heating mat: cable woven onto a mat, simply unrolled across the floor
- Loose heating cable: flexible to position around obstacles (bath, toilet, cupboards)
Materials for electric underfloor heating (bathroom 8 m²)
| Material | Price |
|—|—|
| Heating mat 8 m² (150W/m²) | €60 – €120 |
| Thermostat (with floor sensor) | €30 – €100 |
| Tile adhesive or fibre cement | €20 – €40 |
| Connection cable (to consumer unit) | €10 – €20 |
| Total | €120 – €280 |
Step-by-step guide: electric underfloor heating (bathroom)
Step 1: Plan the layout
Draw the bathroom floor plan on paper. Mark the fixed positions: toilet, washbasin, bath, shower. The heating mat must not go under fixed furniture or appliances — this causes overheating.
Calculate the heated area. This determines the wattage of the mat. Guideline: 150W per m² for bathrooms.
Step 2: Check the consumer unit
Electric underfloor heating draws power. A 1200W mat (8 m²) draws approximately 5.5A. Check whether your consumer unit has a spare circuit (10A) and whether the connection cable can handle it.
Have the connection to the consumer unit carried out by a certified electrician — this is a legal requirement in the UK. Installing the mat itself can be done by you.
Step 3: Lay the mat
Roll out the mat on the clean, dry concrete floor. Start at the thermostat feed point. Make curves in the mat at obstacles — never cut across the cable or trim any sections.
Make sure the mat lies flat and that the cable doesn’t cross itself. Tape the mat loosely to the concrete floor to prevent it shifting during tiling.
Step 4: Lay the floor sensor
Place the floor sensor (supplied with the thermostat) on the mat, midway between two cable loops. The sensor measures the floor temperature and prevents overheating.
Step 5: Finish with tiles
Apply a layer of tile adhesive over the mat (4–6 mm thick) and then lay the tiles. Ensure there are no air pockets under the tiles — air conducts heat poorly and creates hot spots.
Tip: use a notched trowel for the correct adhesive thickness and press each tile down firmly.
Step 6: Install the thermostat
Remove the existing socket or switch and fit the thermostat. Connect the heating cable, the floor sensor, and the power supply to the thermostat (follow the wiring diagrams supplied).
Programme the thermostat: set the desired temperature and times. Typical settings: 20–24°C when in use, 16–18°C on standby.
Wet underfloor heating: step-by-step guide (retrofit system)
Wet underfloor heating in an existing house can be installed by two methods:
Method 1: System board (dry system)
System boards are insulation panels with a groove pattern. The water pipes sit in the grooves — no concrete screed needed. Ideal for renovations.
Advantages: low build-up height (15–25 mm), quick to install, no wait time for concrete
Disadvantages: more expensive per m² than wet system, lower heat output
Method 2: Wet system (screed)
Conventional system: pipes are laid and then covered with a screed (approx. 50 mm). Most efficient method for new builds or major renovations.
Advantages: best heat output, cheaper per m² than dry system
Disadvantages: long drying time for screed (3–6 weeks), raises floor level
Step-by-step guide wet underfloor heating (retrofit with system boards)
Step 1: Remove existing floor covering. Check the sub-floor for level.
Step 2: Lay insulation (if not already present). Minimum 30 mm PIR insulation — without it you’ll be heating the foundations rather than the room.
Step 3: Lay the system boards. Press the boards onto the floor and clip them together. Mark the groove lines for the pipes.
Step 4: Lay the PERT/AL/PERT or PEX pipes in the grooves. Follow the pipe layout drawing (pipe spacing 10–15 cm for good heat distribution). Connect to the manifold.
Step 5: Carry out a pressure test. Set the pressure to 4–6 bar and leave for 24 hours. No pressure drop = no leaks.
Step 6: Have the connection to the boiler or heat pump carried out by a registered installer. This is a legal requirement.
Step 7: Lay the floor covering. Suitable for underfloor heating: tiles, engineered timber (max. Rλ 0.15), laminate (check manufacturer’s specifications), LVT / vinyl flooring.
Floor coverings and underfloor heating
Not every floor covering is suitable for underfloor heating:
| Floor type | Suitable? | Points to note |
|—|—|—|
| Tiles | ✅ Excellent | Best heat output |
| LVT / vinyl | ✅ Good | Check max. temp. (28°C) |
| Laminate | ✅ Good | Check manufacturer’s specifications |
| Engineered timber | ✅ Good | Max. 27°C, low Rλ value |
| Solid timber | ⚠️ Limited | Dry climate only, less suitable |
| Carpet | ❌ Not suitable | Blocks heat output |
| Cork | ❌ Not suitable | Too high insulation value |
Common mistakes
- Heating mat under fixed furniture. Causes overheating and damage to the mat.
- Insufficient insulation beneath the floor. Without insulation you lose 40–60% of the heat to the foundations.
- Wrong floor covering. A thick covering with a high Rλ value blocks the heat.
- No pressure test on the water circuit. A leak after the screed or tiles is a disaster.
- Switching on immediately after installation. Allow screed and tiles to cure fully before turning the system on.
Frequently asked questions
Can I install underfloor heating myself?
Electric heating mat: mostly yes. Laying the mat and connecting it to the thermostat can be done yourself. The connection to the consumer unit must be carried out by a certified electrician.
Wet underfloor heating: laying the pipes and the system boards can be done yourself. The connection to the boiler or heat pump must be carried out by a registered installer.
How much does underfloor heating cost to run per month?
Electric: for a bathroom of 8 m² running 2 hours per day, expect approximately €15–€25 per month (depending on the electricity rate). Wet underfloor heating combined with a heat pump is 3–5 times cheaper to run.
How quickly does underfloor heating warm up?
Electric: 20–45 minutes (depending on floor thickness and floor covering type). Water: 1–3 hours. Programme the thermostat using a timer so the floor is warm before you use the room.
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