All hardwood products absorb moisture from the air, and when this happens, the wood swells. The higher the moisture content in the wood, the more swollen the wood will become. When the moisture content in the wood drops, the wood shrinks. This shrinking and swelling is natural and happens in all homes with hardwood floors. During the winter, small gaps may appear between floorboards as they shrink. In the summer, the gaps will disappear as the boards absorb humidity from the air.