Until recently, ignorance and reticence have prevailed in respect of using underfloor heating for carpeted floors. The previous industry ‘standard’ has been to advise that the carpet and underlay should not exceed a tog rating of 1.5.

However, new research conducted by BSRIA in Bracknell and funded by the Carpet Foundation in conjunction with the Underfloor Heating Manufacturers Association (UHMA) has proved conclusively that any carpet can be used with an underfloor heating system without impairing the performance of the system.

The work showed that none of the five carpets tested (wool-rich Axminster, wool-rich cut-pile Tufted, wool-rich loop-pile Tufted, synthetic loop-pile Tufted and synthetic cut-pile Tufted carpets) laid over waffle sponge rubber or crumb rubber underlay interfered with the efficient warming of the airspace in the 16m² test room above.

It is now a fact that any carpet and underlay system with combined thermal resistance of not exceeding 2.5 tog allows the underfloor heating system to operate efficiently.

New indications are that for the majority of carpet styles the thermal resistance will be less than 1 tog. Thus the majority of carpet and underlay combinations (excluding felt underlay) will generally be less than 2.0 tog and thus suitable for use with underfloor heating.

BSRIA’s findings show that the previous double plate test method was of no value when it came to underfloor heating. Similarly, the tested tog values of the carpets (using the BSRIA test chamber as a life size 'tog' meter) were significantly lower than the previous laboratory test values. The new findings discredit the previous industry standard of 1.5 tog.

Consumers can now be reassured that carpet and underfloor heating systems can operate effectively and efficiently together.