What is the maximum tog rating for carpet over underfloor heating?

Most underfloor heating manufacturers specify a maximum combined tog rating (carpet + underlay) of 2.5 tog. For optimal efficiency, aim for 1.5 tog or less. Always check your specific UFH manufacturer's guidelines.

Can I use wool carpet with underfloor heating?

Yes, but only thin, flat-woven wool carpets. Thick wool saxony or deep pile wool carpets are generally not suitable. A flat-woven wool carpet with a tog rating of 1.0–1.5 paired with a low-tog UFH underlay can work well.

What happens if I use the wrong carpet with UFH?

Using a carpet with too high a tog rating can cause the UFH system to overheat, which may trigger the thermostat to cut out repeatedly, reducing efficiency. In extreme cases, it can damage the heating elements. It also means your floors take much longer to reach temperature.

Do I need special underlay for underfloor heating?

Yes. Standard foam underlay is not suitable for UFH. You need underlay specifically designed for use with underfloor heating — look for a tog rating of 1.0 or less and check it's labelled as UFH-compatible.

Can LVT be used with underfloor heating?

Yes, LVT is one of the best flooring choices for underfloor heating. It conducts heat efficiently, is dimensionally stable under temperature changes, and is available in beautiful designs. Most LVT products are compatible with UFH up to 27°C floor temperature.

Technical Guide 6 min read

Can You Use Carpet with Underfloor Heating?

Yes — but not all carpets are compatible with underfloor heating. Choose the wrong carpet or underlay and you'll either overheat your system, waste energy, or damage your floor. Here's exactly what you need to know.

By the Multi-Save Carpets team · Updated 2025 · Based in Bristol since 1955

The Key Factor: Tog Rating

Thermal resistance is measured in togs. The combined tog rating of your carpet and underlay must not exceed 2.5 tog for most underfloor heating systems. Many manufacturers specify a maximum of 1.5 tog for optimal efficiency.

Every carpet and underlay has a tog rating on its specification sheet. When choosing carpet for a room with UFH, always check this figure and add the carpet tog to the underlay tog to get the combined total.

As a rule of thumb: the thinner and denser the carpet, the lower the tog rating and the more compatible it is with UFH.

Which Carpet Types Work Best?

Flat-woven carpets (such as sisal, seagrass and woven wool) have the lowest tog ratings and work excellently with UFH. They allow heat to pass through efficiently.

Short-pile twist carpets (10–12mm pile height) work well with UFH. They feel comfortable underfoot while maintaining good thermal conductivity.

Loop pile carpets (Berber) can work with UFH if the pile is not too thick. Check the tog rating carefully.

Deep pile saxony or shaggy carpets are generally not suitable for UFH. Their thick pile insulates the floor too effectively, reducing heating efficiency and potentially causing the system to overheat.

Choosing the Right Underlay

Standard foam underlay is not suitable for underfloor heating — it insulates too well. You need a specialist UFH underlay with a low tog rating.

Look for underlay specifically labelled as "suitable for underfloor heating" with a tog rating of 1.0 or less. This leaves enough headroom to add a carpet with a tog rating of up to 1.5 and stay within the 2.5 total maximum.

Rubber crumb underlay is often a good choice for UFH — it has a lower tog rating than foam and is more dimensionally stable under temperature changes.

Electric vs Water UFH: Does It Matter?

The same carpet and underlay rules apply to both electric mat systems and wet (hydronic) underfloor heating. The key difference is that wet systems heat up and cool down more slowly, so the temperature fluctuations are less extreme and carpet compatibility is slightly more forgiving.

For electric systems, it's especially important to stay within the tog limits as the heating elements can reach higher temperatures more quickly.

Practical Tips for Carpet Over UFH

Always let a new UFH system run for at least 7 days before laying carpet to allow any moisture in the screed to fully dry out. Laying carpet over damp screed can cause adhesion issues and mould.

When the carpet is first laid, run the UFH at a low temperature for the first few days and gradually increase to normal operating temperature. This allows the carpet to acclimatise and prevents buckling.

Have your UFH system checked by a heating engineer before laying new carpet to ensure it's operating correctly and within safe temperature limits.