Some materials used for subfloors are vinyl, carpeting, wood and concrete. Homeowners can choose to install engineered-wood flooring over a wood subfloor or concrete slab.
A solid substructure is important for a ceramic-tile floor, as subfloors in a new home are susceptible to damage caused by settling. Vinyl and carpeting are flexible materials that can tolerate engineered floor truss systems with bigger joist spacings, such as 24 inches on the center. Porous manufactured boards, such as oriented strand boards, should not be used for subfloor, as they absorb moisture and tend to expand and contract, causing tiles or grouts to crack. For laminate floors, which are installed to float, a clear, thin plastic sheet underlayment allows the flooring to float freely. Homeowners can also choose to install vinyl, carpeting and laminate flooring over different subfloor materials, such as wood and concrete.
Solid wood flooring is typically nailed to a plywood or oriented strand board subfloor over wood joists or slab-on-grade foundation. Solid wood is not advisable for below-grade installations, especially basements. Homeowners should ensure that the hired tile contractor is going to follow the recommendations of the American National Standards Institute or the standards published by the Tile Council of America in the Handbook for Ceramic Tile Installation.