When parquet becomes cracked in winter, the humidity in the room is not right. It is mostly not due to the quality of the parquet! The natural product wood can bind and release water again (hygroscopicity). The wood moisture with which parquet is supplied and laid is about nine percent with a deviation of 2 percent upwards and downwards (depending on the type of parquet, different limits apply). In order for this condition to remain unchanged, a humidity of 55 to 60 percent is required. These factors change due to the weather and the heating behaviour. This creates small cracks, which, however, recur again in a proper indoor climate. You should avoid strong temperature fluctuations during heating. A good prevention is a humidifier, preferably a so-called evaporator, which keeps the humidity constant at the level of 55 to 60 percent.