Carpet for underfloor heating: choosing the carpet and underlay together
For anyone with a heated floor, or planning one, who wants a warm, soft floor without blocking the heat underneath.
Carpet works over underfloor heating when the carpet and underlay are chosen as one build-up. Aim to keep the combined tog under about 2.5 so heat can pass through, use a low tog underlay made for heated floors, and check the heating system's own instructions before anything is ordered.
Written for: homeowners with water or electric underfloor heating in a room they want carpeted
Why tog matters only when the floor is heated
Tog is a measure of how well a material holds heat in. On an ordinary floor a higher tog simply makes a room feel warmer underfoot, which is why it rarely comes up in conversation. Over underfloor heating the logic flips: the heat starts below the carpet, so everything laid on top acts as a barrier between the warm screed or boards and the room.
That is why the useful question is not whether a carpet is suitable on its own, but whether the carpet and underlay together let enough heat through. A thick, dense pile on a cushioned underlay can feel lovely and still leave the room struggling to warm up, with the system running longer to compensate.
Choosing the underlay for underfloor heating
Underlay for underfloor heating is usually the deciding part of the build-up, because standard underlays are designed to insulate. A low tog underlay, typically 6mm to 8mm, chosen specifically for heated floors, keeps the carpet comfortable while passing warmth upwards.
Underlay is stocked at both warehouses, and it can be bought on its own or alongside the carpet. Bring the details of the heating system with you, or mention it in your enquiry, so the underlay is matched to it rather than picked for softness. On the quote, underlay should appear as its own line, which makes it easy to see exactly what is going under the carpet.
- Ask for the tog rating of the underlay, not only its thickness.
- Avoid assuming the thickest or softest underlay is the best option here.
- Check that the underlay suits the carpet's backing as well as the heating.
Which carpets suit a heated floor
There is no single correct carpet. The practical approach is to add the carpet's tog to the underlay's and check that the total stays under about 2.5. A lighter, tighter pile tends to make that easier than a deep, heavy one, but the figure on the product information is what settles it.
Fibre and pile type still matter for the usual reasons: how the room is used, how easy the carpet is to clean and how it feels underfoot. Our guides to pile types and to twist, loop and saxony carpets explain those differences. Once you have a shortlist, compare the tog of each option with the underlay you plan to use.
Check the system before anything is ordered
Underfloor heating systems come with their own guidance on floor coverings, and that guidance takes priority. Some set a maximum tog for the floor build-up, and some describe how the heating should be run before and after a new floor goes down. Find that paperwork, or the installer's details, before choosing.
It also helps to note what sort of floor sits underneath: a solid screed and a timber floor behave differently, and the existing floor height will affect how the new carpet meets doors and adjoining rooms. Include those details with your room sizes so the materials are worked out against your actual floor.
What fitting involves over underfloor heating
The fitting steps are broadly the same as on any floor: the old covering comes up, the base is checked, gripper and underlay go down and the carpet is stretched and trimmed. The difference is care around the heating itself, so the fitter needs to know the floor is heated before work starts. Fixings that go into the floor should only be used where the system allows it.
Kent Carpet Warehouse can arrange fitting through trusted, fully vetted local fitters, and onsite measuring is available in most Kent areas. Mention the heating when you book the measure so it is part of the plan from the beginning. If you are using your own fitter, supply only is also an option.
What affects the cost
The price depends on the room size, the carpet chosen, the specialist underlay and whether fitting is included. A suitable underlay for heated floors is a separate line on the quote, so compare like with like when looking at two prices. If you already have a written quote, bring it in: we will beat any legitimate quote.
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Useful pages for this job
Common questions
- Can you put carpet on underfloor heating?
- Yes. Choose the carpet and underlay together so the combined tog stays under about 2.5, use an underlay made for heated floors and follow the heating system's own instructions.
- What underlay should I use for underfloor heating?
- A low tog underlay, typically 6mm to 8mm, chosen specifically for the system. Underlay is stocked at both warehouses and is shown separately on your quote.
- Does a thick carpet stop underfloor heating working?
- A thick, dense carpet on a cushioned underlay can hold back too much heat. Check the tog of both and keep the total under about 2.5.
- Does fitting take longer over underfloor heating?
- The steps are much the same as any carpet fitting, but the fitter needs to know about the heating beforehand so fixings and preparation suit the system. Mention it when the room is measured.
- What if the range I want is not in stock?
- Stock changes weekly, so call Maidstone on 01622 828445 or Gillingham on 01634 481102 and the team will tell you what is in today and what is close to it.
Match the underlay to your heated floor
Tell us about your heating system and room sizes, and we will help you choose a carpet and low tog underlay from warehouse stock.
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Two Kent warehouses: Maidstone and Gillingham