Solid wood is milled from a single 3/4”-thick piece of hardwood. Because of its thickness, a solid hardwood floor can be sanded and refinished over several generations of use. Solid wood flooring expands and contracts with changes in your home’s relative humidity. Normally, installers compensate for this movement by leaving an expansion gap between the floor and the wall. Base molding or quarter-round is traditionally used to hide the extra space.