7 min read · Updated 21 August 2026
A great many homes across Europe now have underfloor heating (wet or electric), especially those built since 2010. Laying a rug in those rooms is not straightforward: some fibres and some thicknesses block the heat, overload the screed thermally, or distort above 27-28 °C. Here is how to identify a washable rug suitable for underfloor heating, without giving up the tactile warmth of a textile on the floor.
1. Why not every rug will do
Three technical issues stack up on top of an underfloor heating system.
Heat diffusion. Underfloor heating gives out low-temperature heat (water circulating at 35 to 45 °C, screed at 25-28 °C at the surface). The rug must not block that heat by absorbing or insulating it. Thick or very dense rugs create a "blanket effect" that makes the heating inefficient and can cause local overheating.
Thermal stability of the fibre. Above certain temperatures, some synthetic fibres can soften, distort or shrink. Domestic underfloor heating stays below the critical thresholds, but the criterion still needs checking explicitly.
Stability of the non-slip backing. Natural or synthetic latex backing is generally stable up to 30 °C. Above that it can stick to the floor or soften. On a correctly set system (surface at 25-28 °C) there is no issue, but on a badly regulated floor or one with excessive thermal inertia, an unsuitable backing can cause problems.
The technical conclusion: only rugs explicitly approved by their manufacturer for use over underfloor heating should be laid on this kind of floor. For the fundamentals of washable rugs, see washable rugs: the complete guide.
2. 3 technical rules for compatibility
Rule 1: low thermal resistance (RT). The thermal resistance of a rug is measured in m²·K/W. The lower the figure, the better the heat passes through. The recommended threshold for use over underfloor heating is generally RT < 0.15 m²·K/W, which corresponds to a rug with a shallow pile in a conductive fibre. That value may not appear directly on the product page: the explicit note "Suitable for underfloor heating" is enough.
Rule 2: a slim build. The overall thickness of the rug (pile plus backing) needs to stay contained, ideally under 1 cm. Slim rugs (5-8 mm) perform best. Thick rugs (beyond 1.5 cm) block the heat whatever they are made of.
Rule 3: an explicit note on the product page. This is the golden rule. Rather than assessing compatibility yourself, check that the product page for the design you want explicitly says "Suitable for underfloor heating". At Casemira, that note appears on 167 washable designs in the collection (67 %), to be checked design by design.
If in doubt, Casemira customer service is available on 02 59 66 01 35, Monday to Saturday, 8am to 8pm, to confirm compatibility before you buy.
| Criterion | Recommended value | What to check |
|---|---|---|
| Thermal resistance RT | < 0.15 m²·K/W | An explicit compatibility note |
| Thickness | < 1 cm (ideally 5-8 mm) | Product page (the stated figure) |
| Manufacturer approval | "Suitable for underfloor heating" | Product page (the wording itself) |
"On a heated floor, the right rug does not insulate the heat. It lets it through."
3. Recommended materials
Three families of material work well over underfloor heating.
Slim polypropylene (Heat-Set or BCF). A dense, shallow pile, typically 6 to 10 mm thick, naturally water-repellent, colourfast and affordable. It is the material most often approved for underfloor heating at Casemira. See polypropylene rugs: yes it is plastic, but.
Washable polyester-cotton (a blend). A plush feel with a controlled thickness and washability at 30 °C; the blend keeps thermal resistance within acceptable limits. See washable rugs: the complete guide.
Tencel or viscose in a flat pile. On certain handmade designs with a shallow pile (not shaggy), conductivity remains sufficient. Check explicitly design by design, because most handmade viscose pieces are too thick. See Tencel rugs: the eco-premium fibre and silky viscose rugs.
4. Materials and profiles to avoid
Four profiles should be ruled out, or checked with particular care.
Long-pile shaggy. The pile creates an insulating layer that blocks heat diffusion. The vast majority of Casemira shaggy designs are not suitable for underfloor heating. See long-pile shaggy rugs.
Thick, high-density pure wool. Wool insulates (that is exactly its job in cold settings). Over underfloor heating it reduces the efficiency of the system. Some shallow-pile wool designs may be suitable, but check explicitly.
Handmade rugs with a thick cotton backing. The pile plus a dense cotton backing adds up to too much thickness. Prefer handmade pieces with a slim pile and backing, or washable machine-made ones.
A rug with no non-slip backing plus a thick underlay. Rug and underlay together often exceed 1.5 cm. Prefer a rug with a slim built-in non-slip backing (natural latex, no foam).
5. Good habits in daily use
Beyond choosing the right rug, a few habits keep the heating efficient and the rug in good shape.
Bring the temperature up gradually at the start of the season. When you first switch on in autumn, raise the temperature in steps of 1 to 2 °C a day over a week, so the fibre adjusts without thermal shock. The same applies when winding down in spring.
Do not exceed the maximum temperature the rug allows. Most manufacturers recommend a floor surface temperature < 27-28 °C. On a correctly set system that limit is never reached. If in doubt, take an occasional reading under the rug with an infrared thermometer.
Vacuum more often. Warm air circulating under the rug lifts dust and fine particles. Vacuuming once or twice a week keeps the air healthy and protects the pile.
Move the rug every six months. To avoid localised wear over the pipework or hot spots, shift the rug 20 to 30 cm every six months.
For washable designs, keep the rug out of the room for a full wash and dry cycle (24 to 48 hours) before putting it back. The floor should return to its normal temperature during that time. See how to wash a rug in the machine.
6. 167 suitable Casemira designs
In the Casemira washable rug collection (250+ designs), 167 are explicitly suitable for underfloor heating (67 % of the washable catalogue).
| Feature | Detail |
|---|---|
| Designs suitable for underfloor heating | 167 out of 250+ washable |
| Price | 34 € to 549 € (indicative median 84 €) |
| Polyester (incl. blends) | the majority (washable at 30 °C) |
| Slim polypropylene | the ideal profile for underfloor heating |
| Built-in non-slip backing | 240 out of 250+ washable (96 %) |
| Main sizes | 60×100, 80×150, 120×170, 160×220, 200×290 cm |
How to spot a suitable design: the product page states "Suitable for underfloor heating" explicitly in the "Specifications" section (which expands). If that note is missing, do not lay the rug over underfloor heating.
Try before you buy. Eligible washable Easy Clean designs come with a 20×30 cm sample at 10 € each, fully deducted when you buy, with no limit per household. See the sample collection.
Payment and delivery. Klarna in 3 interest-free instalments with no minimum spend. Free delivery on orders of 100 € or more. Dispatched within 24 to 48 hours.
Free returns within 30 days of delivery. See our returns and refunds policy.
Customer service. 02 59 66 01 35, Monday to Saturday, 8am to 8pm, contact@casemira.com. Do call if you want us to confirm that a particular design suits your underfloor heating before you order.
Three Casemira rugs for the living room
Black & Copper Washable Rug - Onyx
Grey and Burgundy Vintage Washable Rug - Terrazzo
Cream Beige Vintage Washable Rug - Sherpa
7. FAQ: rugs and underfloor heating
Your questions about rugs and underfloor heating
Is every rug suitable for underfloor heating?
No. Only rugs explicitly approved by their manufacturer for use over underfloor heating should be laid on this kind of floor. At Casemira, 167 washable designs are explicitly suitable for underfloor heating out of the 250+ in the collection (67 %), to be checked design by design via the note on the product page.
Which materials work best over underfloor heating?
Three families: slim polypropylene (Heat-Set or BCF, a dense shallow pile), washable polyester-cotton blends, and Tencel or viscose in a flat pile. All of them need to stay under 1 cm in total thickness. To avoid: long-pile shaggy, thick pure wool, and handmade rugs with a thick cotton backing.
What is the maximum thickness over a heated floor?
Ideally less than 1 cm (pile and backing combined). Slim rugs of 5 to 8 mm perform best. Beyond 1.5 cm the rug blocks heat diffusion and the efficiency of the system drops significantly.
How do I check compatibility before buying?
The product page must state "Suitable for underfloor heating" explicitly in the "Specifications" section (which expands). If that note is missing, do not lay the rug over underfloor heating. If in doubt, contact Casemira customer service on 02 59 66 01 35, Monday to Saturday, 8am to 8pm.
Do I need an underlay over underfloor heating?
Usually not. An underlay adds another insulating layer that reduces the efficiency of the heating. Prefer a rug with a slim built-in non-slip backing (natural latex, no foam), which removes the need for a separate underlay. 240 of the 250+ Casemira washable designs have a built-in non-slip backing.
Does underfloor heating damage a rug?
Not if the rug is suitable and used sensibly. The good habits: bring the temperature up gradually at the start of the season (steps of 1-2 °C a day), move the rug every six months to avoid localised wear, and vacuum once or twice a week. Free returns within 30 days of delivery if the rug is not right once it is down.
Written by the Casemira team, based in Brittany.
