All new houses have moisture - it's a good idea to get the heating running before laying the flooring, and generally good for the overall building fabric.    To achieve optimal heat output and temperatures, good contact is required between the floor and floor covering and no air gaps should be allowed.    Thick cork and soft woods are unsuitable for floor heating.  Be aware of the suitability of some laminates and how they're fixed to the floor.  It's always a good idea to check with your floor covering manufacturer.

Suitable Floor Coverings

All stone, concrete, screeds, slate, ceramic and quarry tiles allow excellent heat transfer and output.

Bamboo flooring is suitable for use with underfloor heating

Linoleum and vinyl are suitable but should be no thicker than 5mm.  When gluing lino/amtigo to the concrete or screed, ensure the concrete or screed is dry and all moisture is eliminated.  It may be beneficial to have the heating running to help dry out the floor.  Failure to do this can cause condensation to the underside of the flooring. 

All carpets are suitable, however the total carpet thickness including underlay must not exceed 1.5 tog - this is crucial. IHS design calculations are based on 0.9 tog, if you intend to use carpet with a tog higher than this (up to 1.5 tog) we must be notified.  The function of underlay is to prevent wear and tear on the underside of the carpet.  A thinner type of no more than 3mm should be used with no air pockets being allowed to develop between underlay and carpet.  The carpet can be laid loose, tensioned or glued to the floor - if glued, the heat output is higher.

Timber floors with underfloor heating

Wood is a natural material; it will expand and shrink as the moisture content varies.  In order to avoid substantial shrinkage in the wood, its moisture content should be between 6 and 10%.  It's important you take careful note of your floor suppliers' instructions regarding drying out or acclimatising the timber before you commence installation.

IHS recommends the use of hardwood in planks no wider than 80mm and no longer than 1.2 meters.  Total wood thickness should not exceed 22mm.  A number of our customers have however, by their own choice, used boards of 130mm wide and 2.5 meters long and this has been successful.  We think that this is the way the wood was cut and subjected to a slow acclimatisation process.

A good quality damp-proof membrane should be installed below the screed or concrete.  This will stop any new moisture being drawn up from lower layers.  The floor heating should be running for at least ten days to ensure the screed or concrete is dry.  If the concrete/screeded floor is not properly dried out, a high damp tension will occur and condensation will form against the coldest outside layer ie. the wood floor.  This can cause considerable expansion and capping of the wooden floor.

The glue we recommend for this process is Lekol 5500.  This glue contains no water and has a fifteen minute application time depending on temperature.  The heating should be switched off the night before the wood is to be applied, then switched on again twenty four hours after the wooden floor is glued down.    Starting with low temperatures, increase the temperature through the floor over a period of a week, allowing the wood to further acclimatise.  This can be done very easily using the regulating valve on the underfloor heating manifold.  Tongue and groove joints between the boards should not be glued in order to allow shrinkage and expansion to take place.

Please note that IHS does not supply glue or timber flooring.  Refer to floor suppliers' guidelines for advice on applying adhesive.