Underbase for flooring board is a type of plywood used as the substrate for flooring materials. Knot holes, which are unavoidable in softwood plywood, are repaired with putty and the surface is finished to a smooth condition. There are two main types of flooring products: solid wood flooring and engineered wood flooring. The plywood flooring substrate (floor underbase plywood) manufactured by Shimane Plywood offers several advantages over solid wood flooring, including greater resistance to warping, improved resistance to scratches and mold, and lower cost. Its key characteristics are stable strength and minimal dimensional change, and its typical service life is generally considered to be 10 to 20 years.