Timber is a hygroscopic material. This means that timber always tries to reach a moisture content balance in relation to the relative humidity of the ambient air. When the relative humidity of ambient air is rising, timber absorbs water and swells, and when the relative humidity of ambient air is going down, timber releases its water and shrinks. Recommended air humidity is at least 35 %.
When delivered from the factory, wood flooring has a moisture content corresponding to the humidity of an apartment that is central heated. During winter time, when the central heating system is fully utilised and the absolute humidity of the open air is very low, relative humidity indoors goes down and may cause an opening of the wood floor joints and small cracks in between the boards. During spring and summer time, when the relative humidity goes up again, joints close by themselves. This proves that wood flooring is manufactured from nature's own materials and does not contain synthetic components.
Due to the hygroscopic properties of timber, relative humidity of the ambient air should always be as stable as possible i.e. 40 - 60 % and temperature should be 18 - 24 ° C. These are ideal conditions, not only for wood flooring but also for you.