Underfloor Heating and Engineered Wood Flooring – What Conditions Are Necessary?

All homes have their own indoor climate which is determined by factors like the amount of moisture in the air (humidity), the temperature, the type of heating and the amount of ventilation. In a comfortable home with slight humidity variation through the seasons, wooden floors react by expanding and shrinking. During warm, humid weather wood expands. During dry weather wood shrinks – this seasonal movement is a normal characteristic of wooden floors and it never stops, regardless of the age of the wooden floor.
This movement of the boards can be significantly reduced by proper acclimatisation and by keeping temperature and humidity levels as even as possible throughout the year. Flooring machined with a bevel will show less evidence of movement than a square edged material.
Indoor air quality is greatly influenced by the temperature and relative humidity of the air, with a relative humidity of between 45% and 60% considered to be the most healthy and pleasant. However, central heating and dry winter air can combine forces to reduce indoor humidity levels to below these recommended levels. The more intensively you use central heating or underfloor heating, the dryer the air becomes and this has a detrimental effect on everything in the house – people, furnishings and floors.
The moisture content of the timber flooring needs to be in equilibrium (i.e. balanced) with the humidity levels of the air in the room. The optimum relative humidity (RH) of the air in a room with timber flooring should be between 45-65% – certainly not lower than 40%. This ensures minimal shrinkage and expansion of the timber.
Following installation, the floor temperature should only be raised very gradually from a low starting point. Ideally, the floor should be a consistent temperature throughout with no hot spots. Large rugs can lead to a build-up of heat and consequent damage to flooring – they should either be removed or selected for compatibility with underfloor heating.
We recommend that you buy a hygrometer and a programmable humidifier / vaporizer and keep a close eye on humidity levels, especially during the cold, dry winter months so that the humidity level does not drop below 40% RH. Relative atmospheric humidity should be maintained between 40% and 65% using the humidifier if necessary.
Temperature control is also important. No timber likes to be over heated and baked dry. The recommended temperature in a room with wooden flooring is between 18 – 24 degrees Celsius – with an absolute maximum surface temperature of 27 degrees Celsius.
The above recommended optimum relative air humidity and temperature levels should be observed at all times. Please look at our website for further information – particularly the facta and figures box on the underfloor heating page (see addresses below).