Underfloor Heating Installation

Underfloor heating has to be sized to the room, suited to electric or wet depending on the build-up available, and commissioned gradually once the tile adhesive has cured — not switched straight to full heat on day one. From £3,500.

A cold tiled floor is one of the most common complaints we hear about an otherwise well-finished bathroom, and underfloor heating is the fix most clients ask for once they've lived with it. The system itself — mat, cable or pipe — is only half the job; getting the floor build-up, insulation and control right is what decides whether it actually warms the room or just takes the chill off the tile surface, particularly first thing in the morning when the difference is most noticeable.

Electric or wet: which suits your project

Electric underfloor heating is the right call for the majority of bathroom refits. It has a low build-up height, so it rarely causes a problem with door thresholds or adjoining floor levels, it's cheaper to install, and for a room that's only occupied for short periods each day, its slightly higher running cost per hour isn't usually significant. It's also the only realistic option when retrofitting into an existing floor without opening up the whole structure.

Wet underfloor heating costs more to install because it needs pipework, a manifold, and usually a screed floor build-up, but it runs more cheaply over time and suits a larger bathroom or a full renovation where the floor is already being rebuilt from joist level. If you're planning a full strip-out and the budget allows, it's worth discussing at survey — but retrofitting a wet system into a finished floor rarely makes sense once the build-up height is accounted for. See our electric vs wet underfloor heating guide for the full comparison.

There's a middle ground worth knowing about too: low-profile wet systems with thinner pipework and a reduced screed depth, designed specifically for renovation projects where a full structural floor build-up isn't practical. They cost more than electric mats and still need a connection to the heating system, but add less height than a conventional wet install. We'll discuss whether this fits your floor at survey if a wet system is what you're leaning toward.

How it runs

1. 1
   Survey (£125). Floor construction, available build-up height and electrical capacity are checked against electric and wet options.
2. 2
   Insulation and layout. Insulation board is fitted and the mat or pipe run planned around fixed fittings.
3. 3
   Fitting and testing. The system is laid, connected, and electrically tested or pressure tested before anything covers it.
4. 4
   Tiling over the system. Floor tiling proceeds once the heating element is confirmed intact and protected from damage during laying.
5. 5
   Cure and commission. Once adhesive and grout have fully cured, the system is brought up to temperature gradually and the thermostat programmed.

Common mistakes we see on previous installations

The most frequent fault we're called to investigate is a mat that was never properly recorded — no photograph of the layout, no continuity reading taken before tiling, and no indication of where the sensor cable or joints sit beneath the floor. When something later needs drilling into, nobody knows what's underneath. We photograph and record every heated area before covering it, and keep that record with the job file so any future work — a new vanity unit, a shelf fixed to the floor, a plumbing alteration — can avoid damaging a live cable.

The second common fault is heating laid under fixed furniture, such as beneath a vanity unit or WC pan, where it serves no purpose and simply wastes energy and shortens the system's working life through heat it can't usefully dissipate. We map the layout against the final fitted positions at survey stage, not after the floor's already down, so heating only goes where it's actually needed. A third, less obvious issue is a thermostat set without a floor temperature limit, left to run on an air sensor alone — over months this can push certain adhesives and natural stone beyond their tested range, which is why we always commission with a floor sensor and a sensible upper limit in place.

What affects the price

Electric underfloor heating as part of a full bathroom refit, where the floor is already being tiled, adds relatively little to the overall project. A wet system costs considerably more due to the pipework, manifold and screed involved. Room shape also matters: an irregular floor plan with multiple fixed fittings to route around takes longer to lay than a simple rectangular room, and a split-level floor or a step up into a shower area adds further layout complexity. We confirm the specific figure at survey once floor area and system type are agreed.

What you supply

The underfloor heating kit (mat, cable or wet system) and thermostat are typically specified and supplied as part of our installation given how closely the system has to match the floor area and tile type, but if you've already sourced one, bring the full spec — output, cable spacing and thermostat model — to survey so we can confirm it's compatible with your floor build-up and chosen tile or stone.

If supplying your own tiles or stone separately, confirm maximum operating temperature with the manufacturer, since some natural stone and engineered products have specific limits that the thermostat needs to be set within.

Where the thermostat is being chosen separately — a smart, app-controlled model rather than a basic dial — check it's compatible with the mat or cable's sensor type before ordering. Some smart thermostats expect a two-wire floor sensor and won't read correctly from older three-wire sensors still supplied with certain mats, which is a mismatch better caught before delivery than on install day.

Frequently asked questions