STONE & CERAMIC TILES
Tiles are generally considered to be the best floor finish for use with
underfloor heating due to their excellent heat emitting properties. Both stone
and ceramic tile types have very good thermal conductivity and allow for a
consistent and comfortable heat to be transferred.
If you are planning to lay tiles it is recommended that a flexible grout is
used. Specialist UFH grouts are widely available now.
Further information regarding tiling onto underfloor heating systems can be found on The Tile Association website - http://www.tiles.org.uk/
WOOD & LAMINATE FLOORS
All types of wood flooring can be used with underfloor heating but some are more suitable than others. Consideration should be given to the expansion and contraction as a result of changing moisture levels.
The BSRIA Underfloor Heating System Guide states the following rules in relation to wood floors:
It is also important to know that wood is a good natural
insulator so the interface temperature will be higher than for masonry systems.
A relevant standard is BS8201:1987 Code of Practice for Flooring of Timber, Timber Products and Wood Based Panel Products.
CARPET & UNDERLAY
Carpets can be used as an effective floor covering with underfloor heating.
However, it is important to understand the TOG values of products and the
requirements for using low TOG rated carpet and underlay to achieve the best
The thermal performance of carpet and underlay is measured in TOG. A TOG value is equivalent to the thermal resistance (measured in W/m2K) multiplied by 10.
The Underfloor Heating Manufacturers Association states that a combined carpet and underlay TOG value up to 1.5 is safe for low temperature systems but values can go up to 3.5 for higher temperature flow.
It is common practice to select a TOG of 2.5 or below. Select an underfloor friendly underlay; your carpet supplier should be able to help. A suggested 5mm of underlay and 10mm of carpet would broadly equate to this but it is a rule of thumb and likely to vary depending on carpet style.
In general, laminate flooring is suitable for use with a underfloor heating system providing the thermal resistance of the high density fibreboard (HDF) and the cushion layer are taken into account and extra allowance is given for thermal expansion at the edges.
Several manufacturers produce low thermal resistance products specifically for underfloor heating applications.