Being an organic material, wood is described as being “hydroscopic.” This means that it will react to water and humidity by expanding and contracting. Too much humidity in the air will increase the moisture content in the wood and create expansion in the wood. Too little humidity in the air, such as drying caused by heating during the winter, will cause moisture to come out of the wood resulting in shrinking between the floor boards.
Air conditioning, heating, and ventilation systems should be operating before, during, and after work is performed. The temperature and relative humidity should be at normal occupancy level, between 68-80 degrees (F) and the humidity level should be between 30-50 percent. Use a hygrometer (relative humidity indicator) to check moisture content in the air to ensure that relative humidity is within the recommended range.
