Wood is a natural product that responds to its environment. it is a hygroscopic material, which means that it will lose or gain moisture until it is in equilibrium with the air surrounding it. in dry conditions, such as during winter months when heating systems are in use, wood floors will shrink, which will result in gaps between floor boards. In wet condition, such as during summer months when humidity is higher, wood floors will swell. This is a normal reaction of wood floors that will occur from season to season. You can minimize these changes in your wood floor by maintaining your home between 60-80 degrees Fahrenheit and 30-50 percent humidity year-round.