Underfloor Heating & Wooden Floors
If you are thinking about under-floor heating with your hardwood flooring there are many factors which must be considered before you make your final choice of both wood and heating system.
Electrical Matting Systems
The easiest and quickest systems to fit are electrical matting systems, which sit directly under your hardwood floor and are wired via a thermostat into your mains electricity. These systems are very effective and are compatible with all floating engineered floors. They give very even heat distribution and are less prone to hot spots and therefore less likely to cause the hardwood floor to fail.
Hot Water Pipe Systems
The second type of under-floor heating system is the hot water pipe system, which is run in the same way as your central heating system. Usually the pipes will be laid in a concrete screed, although they can be run between joists with metal dispersion plates.
When fitting a hardwood floor on top an under-floor heating system within a concrete screed, no attempt must be made to lay the floor until the relative humidity of the concrete has reached 75% or below. The only way to test for this is
(a) by drilling into the screed and inserting plastic plugs, then returning after 24 hours to take readings, or
(b) by use of a humidity box.
Once this level of relative humidity has been reached, and the under floor heating system has been fully tested and has been working for twoweeks, then - and only then - can the flooring be acclimatised. Acclimatisation must take place with the underfloor heating running and with the surface temperature of the sub floor not above 27 degrees centigrade. For the sub floor surface temperature not to exceed 27 degrees centigrade the hot water in the pipes under the floor must be cooled at the manifold accordingly. It is vital to get this calibration right at this point, it will avoid damaging the floor in the future.
Only engineered floors are stable enough to fit with hot water pipe under-floor heating systems, and for the very best results we strongly recommend that the floor be stuck down using an MS Polymer adhesive.
There are two reasons for this: first, you will get a much better heat transfer when the floor is stuck directly to the screed (putting down a plastic membrane followed by an underlay and then the floor will be like layers of blankets on a bed and will trap the heat under the floor); second, by fully bonding the floor to the concrete you are minimising any possibility of movement, which will always be greater in a floor fitted over under floor heating.
Prior to installation the under floor heating system must be turned down to the desired installation temperature of 18°C. On completion of the installation the under floor heating system must be left running at the installation temperature for a minimum of four days to allow the adhesive to fully cure at its optimal temperature.
At the end of this four day period the heating can then be increased at increments of no more than 1°C each day until the desired temperature is reached, bearing in mind that the surface temperature of the floor should never exceed 27°C.
Whenever the heating is to be turned up or down in the future, it must always be done in increments of +/- 1°C per day to avoid undue stress on the floor as it adjusts to the new temperature. Always use specialists to fit a floor with under floor heating.