This guide covers the full job: measuring up, preparing the floor, laying insulation and mats, choosing a carpet that lets the heat through, and getting the system signed off and switched on. The system is fitted in more than 100 UK homes and carries a 15-year warranty, honoured directly by the UK importer.
One thing before you start. Laying the mats is genuinely DIY-friendly. The final electrical connection is not. A qualified electrician must connect the system to the mains and certify the work under Part P of the Building Regulations (BS 7671). Plan for that from day one and everything else is straightforward.
Tools and materials checklist
- AHT ribbon heating mats to suit your layout (0.5m wide at £45/m², or 1m wide at £65/m²)
- Therm-All insulation boards (£53.50 per 10m² pack)
- WiFi touchscreen thermostat with floor sensor (£89.99)
- Low-tog underlay rated for underfloor heating (from your carpet supplier)
- Tape measure, pencil and paper (or the free online room designer)
- Sharp knife and straight edge for cutting insulation boards
- Broom or vacuum for the subfloor
- Tape for insulation board joints
- A qualified electrician booked for the final connection and Part P certification
Planning and measuring the room
Get the planning right and the rest of the job is easy. Start with a sketch of the room. Mark anything fixed to the floor, like built-in wardrobes or fitted units. Do not plan heating under those. Heat trapped under fixed furniture is wasted, and leaving those areas cold is standard practice across the industry.
Next, decide what the heating is for. If it is comfort heating on top of radiators, cover the areas where you walk and sit. If it is the main heat source for the room, cover at least 70% of the floor. That 70% figure is the minimum for the ribbon to work as primary heating.
The mats come in two widths. 0.5m wide mats run from 1m to 7m long and cost £45 per square metre. 1m wide mats run from 1m to 3.5m and cost £65 per square metre. Narrow mats suit awkward rooms. Wide mats cover big open floors faster.
Leave a clear border around the edge of the room for the carpet gripper rods. Grippers are nailed down, and nails and heating mats do not mix. Plan your mats to stop short of the gripper line on every wall.
If you would rather not do the maths, use the free room designer. Draw your room and it gives you the exact ribbon layout and the price.
What you need
The shopping list is short. Ribbon mats to suit your layout, Therm-All insulation at £53.50 per 10m² pack, and the WiFi touchscreen thermostat at £89.99. Add a low-tog underlay rated for underfloor heating from your carpet supplier. The full list is above.
Notice what is not on the list. No screed, no self-leveller, no wet trades. The ribbon lays dry, straight onto the insulation. There is more on why that matters in our no-screed guide.
Tools are basic: tape measure, sharp knife for the insulation boards, broom or vacuum for the subfloor. UK delivery is free on orders over £150, or £9.99 under that.
Step-by-step: how to install underfloor heating under carpet
- Plan your layout. Measure the room and mark where fixed furniture sits. For primary heating, plan mats over at least 70% of the floor. The free room designer draws the layout and prices it for you.
- Prepare the subfloor. Lift the old flooring and clear the subfloor completely. Pull out old staples, nails and gripper tacks, then sweep and vacuum. The surface must be clean, dry and flat before anything goes down.
- Lay the insulation. Lay Therm-All insulation boards edge to edge across the area you plan to heat, and tape the joints. Insulation pushes the heat up into the room instead of losing it into the subfloor. It makes the system cheaper to run and faster to warm up.
- Roll out the ribbon mats. Roll the mats out over the insulation following your plan. Keep them clear of the gripper line around the room edge and away from fixed furniture. Never cut or shorten the heating element itself, and never overlap mats.
- Fit the floor sensor and route the cables. Place the thermostat floor sensor between two ribbon runs, not on top of one. Route the sensor lead and the mat cold tails back to the thermostat position on the wall.
- Get the electrician in. A qualified electrician connects the mats and floor sensor to the thermostat and the mains, then tests the circuit. This must be done to BS 7671 and certified under Part P. Book it before the carpet goes down, so any fault is found while the floor is still open.
- Fit the protection layer and underlay. Once the electrician has tested everything, cover the mats with a low-tog underlay rated for underfloor heating. Ask your carpet supplier to confirm it suits electric systems before you buy.
- Fit the carpet. Have the carpet fitted as normal, but tell your fitter the floor is heated. No gripper rods, nails or staples anywhere near the mats. If the fitter has not worked over underfloor heating before, walk them through your mat layout first.
- Run the first heat-up. Switch the system on at a low temperature and bring it up gradually while you check the room heats evenly. There is no screed to dry out, so there is no long commissioning wait. Then set your daily schedule on the WiFi touchscreen thermostat.
Choosing the right carpet and underlay
This is where carpet installs succeed or fail. The heat has to pass through the underlay and the carpet to reach the room. Every layer adds resistance, and that resistance is measured in tog.
The general industry guidance is simple: keep the combined tog of carpet plus underlay low. A combined figure of around 2.5 tog or less is commonly quoted across the UK flooring trade. Ask your carpet supplier to confirm that both the carpet and the underlay are suitable for electric underfloor heating before you order. Any decent supplier will know straight away.
Underlay matters more than most people expect. Thick felt underlay feels warm and soft underfoot precisely because it blocks heat, which is the opposite of what you want here. Look for an underlay sold specifically for use with underfloor heating. They are widely available from carpet and flooring suppliers.
The carpet itself gives you more room for choice. Most mainstream carpets work well as long as the combined tog stays low. Check the manufacturer's guidance for your exact carpet, and keep a note of the tog ratings in case you change the carpet later.
Common mistakes to avoid
These are the errors that damage mats or leave rooms lukewarm. All of them are avoidable.
- Gripper rods through the mat. Grippers are nailed into the floor, and a nail through a mat ruins it. Plan the mats to stop short of the gripper line on every wall, and tell your carpet fitter the floor is heated before they start.
- High-tog felt underlay. It insulates the room from your heating. Use a low-tog underlay rated for underfloor heating, nothing else.
- Heating under fixed furniture. Wasted money and trapped heat. Plan around wardrobes and fitted units from the start.
- Cutting or shortening the heating element. You can plan mats to fit almost any room shape, but the heating element itself must never be cut. If your layout does not work, change the mat sizes, not the mat.
- Connecting it yourself. The final connection is a job for a qualified electrician, certified under Part P (BS 7671). No exceptions.
- Carpet down before testing. Have the electrician test the system while the floor is open. Finding a fault after the carpet is fitted means lifting it again.
What it costs: a 14m² lounge example
Take a typical lounge, 4m x 3.5m, which is 14m² of floor. To run the system as primary heating you need at least 70% coverage, which is 9.8m². Four 0.5m x 5m ribbon mats give you 10m² of heated floor, comfortably over the line.
- Four 0.5m x 5m ribbon mats, 10m² at £45 per m²: £450
- One Therm-All insulation pack, covers 10m²: £53.50
- WiFi touchscreen thermostat: £89.99
Total: £593.49, with free UK delivery because the order is over £150. If you want the whole 14m² floor insulated rather than just the heated area, add a second insulation pack at £53.50.
On top of that, budget for your electrician's connection fee and your carpet and underlay. Those vary by area and by carpet choice, so get local quotes. Even so, just under £600 for the complete heating kit in a full-size lounge compares well with most ways of adding heat to a room.
Next steps
Every room is different, which is why we built the room designer. Draw your room and it gives you the exact ribbon layout and price in minutes. You can browse the full range in the shop, or read the complete electric underfloor heating guide if you are still comparing systems.
Not sure about something in your room? Call us on 07883 298944. We are EkoBuild, AHT amorphous ribbon specialists based in Flint, North Wales, and we would rather answer a question before you order than after. Every system carries a 15-year warranty, honoured directly by the UK importer.
FAQs
Can you fit electric underfloor heating under carpet?
Yes, with the right system. The AHT ribbon mats are 1.8mm thin and lay directly under carpet with no screed or self-leveller. You lay insulation, roll out the mats, add a heating-rated underlay, then fit the carpet on top.
What tog rating should carpet and underlay be for underfloor heating?
General industry guidance is to keep the combined tog of carpet and underlay low, usually around 2.5 tog or less, so the heat can pass through into the room. Thick felt underlay is the usual cause of blocked heat. Always confirm suitability with your carpet supplier before you buy.
Can underfloor heating under carpet be my main heating?
Yes. The AHT ribbon runs at 150W per square metre, and to use it as the primary heat source for a room the mats must cover at least 70% of the floor. The room designer at ekobuild.co.uk/room-designer works the coverage and price out for you.
Do I need an electrician to install underfloor heating?
Yes, for the final connection. Laying the insulation and mats is DIY-friendly, but the connection to the thermostat and mains must be made by a qualified electrician and certified under Part P of the Building Regulations (BS 7671). Budget for this when you plan the job.
Do I need screed or self-leveller under carpet?
No. The AHT ribbon system lays dry, directly under the flooring, so there are no wet trades, no drying time and minimal added floor height. Once your electrician has connected and tested the system, the carpet can go straight down.