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Electric underfloor heating in a bathroom

Updated: 22 October 2026

You are tiling a small UK bathroom and the mat size on amazon.co.uk still shows whole-room square metres. Electric underfloor heating in a bathroom starts with the walkable floor around the bath, not the room name on the plan. This page keeps to that one room: free-floor maths, the 150 W versus 200 W disagreement sellers publish, what the small captured mats include, and England’s Part P notification tests. The nine-row table lives on the [electric underfloor heating comparison](/hub/heating/electric-underfloor-heating). Peter F. compared the listings on 20 October 2026. Nothing was tested in a lab. A qualifying purchase can earn a commission at no extra cost to you.

You are tiling a small UK bathroom and the mat size on amazon.co.uk still shows whole-room square metres.

Our top picks

HEATIT HEATIT 5 m² mat with ET-84 thermostat

Best overall

HEATIT HEATIT 5 m² mat with ET-84 thermostat
7.4/10about £142.49
View offer
HEATIT HEATIT 3 m² 200 W/m² mat

Best value

HEATIT HEATIT 3 m² 200 W/m² mat
8.9/10about £42.99
View offer
HEATIT HEATIT 2 m² mat with ET-81 thermostat

Rank 3

HEATIT HEATIT 2 m² mat with ET-81 thermostat
9.1/10about £99.99
View offer
On this page
  1. 1.Measure around the bath, not the whole room
  2. 2.150 W/m² and 200 W/m² are both sold for bathrooms
  3. 3.What the small captured mats actually include
  4. 4.England’s Part P, and why council pages disagree

Measure around the bath, not the whole room

Heat Mat tells you to measure around floor-mounted fittings, and around a bath unless it is free-standing with an air gap underneath. Deduct shower trays, WCs, basins and boxed-in pipes before any ten-per-cent fitting allowance. BodenWärme’s example rounds a deducted bathroom down to five square metres. That is their bathroom, not yours, and it is why sellers stock 1.5 m², 2 m² and 3 m² rolls. Whole-house measuring sits on the electric underfloor heating buying guide. A 0.5 m mesh may waste area when you turn strips along a narrow wall. This set has mesh mats only, so you may accept imperfect coverage rather than cut the element. Do not heat under the bath, a pedestal or a tray. ThermoSphere calls that thermal blocking.

150 W/m² and 200 W/m² are both sold for bathrooms

Warmup’s 150 W/m² line targets well-insulated rooms as primary heat. Heat Mat prefers 200 W or 240 W/m² for small tiled bathrooms unless you only want to take the chill off the tiles. This set does not settle which wattage your bath needs. Only the five-square-metre HEATIT states 150 W/m². Every other 230 V mesh mat here is 200 W/m². Choose area first, then decide whether a five-square-metre floor is a 200 W/m² kit or a mat-only 150 W/m² trial. A higher output does not remove Quick-Step’s 27 °C laminate cap. These mats name tile and stone first. Bathroom on a listing is not one wattage.
HEATIT HEATIT 5 m² mat with ET-84 thermostat

Testsieger

HEATIT HEATIT 5 m² mat with ET-84 thermostat
7.4/10about £142.49
View offer

What the small captured mats actually include

For about two square metres with the controller in the box, the HEATIT kit with ET-81 at £99.99 states mat plus thermostat, 400 W and 1.7 A, and a shower room while excluding pools and outdoor use. The 1.5 m² HEATIT and MINCOHEAT rows near £33 to £40 do not list a thermostat. The 3 m² HEATIT and bolisi add area, still without a controller in the box, except bolisi’s sensor tube. If the free floor is about five square metres, the ET-84 kit at £142.49 is the large row with a thermostat, and only one rating in the capture. None of these listings proves the metal sheath or earth grid that BS 7671 commentary calls for in some bath locations. They describe fluoropolymer insulation. An electrician judges that on site.

England’s Part P, and why council pages disagree

Approved Document P (2013) for England lists notifiable work as a new circuit, a consumer-unit replacement, or an addition or alteration in a special location such as a bath or shower zone. The IET Part P FAQ says a new heating circuit is notifiable in any room, while an addition to an existing circuit outside a special location is not notifiable on that test. The work still must be safe. Some council pages, including Richmond and Bath and North East Somerset, still describe floor heating and bathrooms more broadly than Westminster’s shorter list. If a council sheet clashes with Approved Document P, ask building control. Scotland and Northern Ireland set their own rules. Connection, RCD protection and zone limits remain electrician tasks. The 12 V vehicle film is not a bathroom product.

Common questions

Do I heat under the bath?
No. Measure around it unless it is a free-standing bath with an air gap you can verify. Do not trap cable under pedestals, trays or boxed-in pipes. ThermoSphere calls heating under a fitting thermal blocking.
What mat size fits a small bathroom?
After deductions, many small UK baths land near 1.5 to 3 m² of walkable floor, which matches the small rolls in this set. If deductions still leave about 5 m², the five-square-metre kits or mats apply. Round down. The cable cannot be shortened.
Is 200 W/m² required in a bathroom?
Some UK suppliers recommend 200 W/m² or more for small tiled bathrooms. Others treat 150 W/m² as enough in a well-insulated room. This page does not pick a single wattage for every bath. Only one captured mat states 150 W/m².
Is bathroom underfloor heating notifiable in England?
A new circuit is notifiable in any room. Work in a bath or shower zone is notifiable when it is an addition or alteration to a circuit in that special location. Exact notification is for building control or a registered installer to confirm on your job. The work still has to be safe when it is not notifiable.
Does the same rule apply in Scotland and Northern Ireland?
No. Scotland and Northern Ireland set their own building and electrical rules. Use England’s Approved Document P only for a job in England. A Glasgow or Belfast bathroom needs the rule that applies there.
Can the mat go in a shower room?
Several HEATIT listings allow wet application and name a shower room while excluding pools and outdoor use. That is seller wording, not a substitute for a zone drawing and an electrician’s sign-off.
Does the 2 m² HEATIT kit include the thermostat?
The listing says one mat and one ET-81 thermostat. That is the captured box claim at about £99.99. Check the live amazon.co.uk page before you order, because a minimat colour line on other HEATIT sizes does not make the same claim.

Related pages

How to install a mat

150 W/m² or 200 W/m²

Electric underfloor heating

Best electric underfloor heating mat for a UK room

Electric underfloor heating buying guide for UK rooms

Sources

Public UK sources named below. amazon.co.uk prices, stars and review counts on these nine listings were taken from the listing files captured on 19 October 2026. Page updated October 2026.

  1. Approved Document P (2013) (retrieved 20 October 2026)
  2. IET Part P FAQ (retrieved 20 October 2026)
  3. Professional Electrician, heating cables (retrieved 20 October 2026)
  4. Voltimum, electric floor heating (retrieved 20 October 2026)
  5. Warmup StickyMat (retrieved 20 October 2026)
  6. BN Thermic, tiles (retrieved 20 October 2026)
  7. Heat Mat, measuring up (retrieved 20 October 2026)
  8. Quick-Step UK laminate FAQ (retrieved 20 October 2026)