When fitting underfloor heating (UFH) in any home, an important consideration for the homeowner and system designer is the floor covering which will be used on top of the floor construction and underfloor heating system.
In general terms, any form of floor covering can work effectively with your underfloor heating system. However, some types of floor covering do work better than others due mainly to their heat transferring abilities.
The best types of floor covering for use with underfloor heating are harder surfaces such as stone or ceramic tiles. These work best because they are the least resistant to heat and are therefore able to transfer heat effectively. The worst kind of floor covering is thick carpet. This is because carpet is designed to insulate and therefore is more resistant to heat transfer. The higher the Tog rating of the carpet, the higher the required heat output of the underfloor heating system is likely to be and this can impact heavily on heating costs. BS1264 states that an underfloor heating system should not be operated at a temperature greater than 29˚C.
Carpet and Underlay with Underfloor Heating
As previously mentioned, carpets are generally good insulators and therefore not good at transferring heat. The higher the Tog rating (1 Tog = 0.1²K/W) of a carpet, the better at insulating and the worse at transferring heat it will be. For this reason, it is best to choose a carpet with a low Tog rating if possible. Open-weave design carpets will not significantly prevent the transfer of heat, but carpets with underlay or a foam backing will prevent heat transfer to a much greater degree. If it is decided that for whatever reason a carpet floor covering is to be used, be sure to opt for a carpet of 1.5 Tog or less.
Vinyl floor coverings with Underfloor Heating
Vinyl floor coverings are usually poor insulators and therefore allow for effective heat transfer. Their high temperature ratings make them perfect for use with underfloor heating systems where a high level of heat transfer is necessary.
Solid Hardwood floor coverings with Underfloor Heating
When using a solid hardwood floor covering with an underfloor heating system, it is important to make sure that the moisture content of the wood is between 6-9%. Using this type of floor covering, one should bear in mind the shrinking and swelling properties of wood and the resulting effects an underfloor heating system could have upon it. Lay the flooring loose in order to allow it to properly settle into place by swelling or shrinking. If laying a floating hardwood floor, it is sometimes recommended by the manufacturer that a thin foam layer be laid beneath the hardwood and the screed. If doing this, be sure to lay only a thin foam layer.
Engineered or Laminate floor coverings with Underfloor Heating
Engineered or laminate floor is a type of wood flooring made up or layers of plywood or MDF beneath a thin hardwood surface. This is usually used due to its thermal stability. An engineered or laminate floor covering is less likely to react to heat or humidity than a solid hardwood floor covering, but should still have a moisture content of between 6-9%. Using this type of floor covering, the surface temperature of the floor should not exceed 27˚C.
Tiled floor coverings with Underfloor Heating
Tiled floors tend to work perfectly with underfloor heating (UFH). Whether ceramic, quarry, stone, or marble, the low heat resistance of tiled floor coverings allow for optimum transfer of heat into the floor and the room above, providing the most comfortable warmth of floor and room.