What is s4s lumber?

S4S lumber stands for "surfaced four sides" lumber, which refers to lumber that has been planed smooth on all four sides. This type of lumber is often used in construction and woodworking projects where a smooth finish is desired. S4S lumber is typically dimensionally stable and is available in a variety of wood species and sizes. It is commonly used for trim, molding, and other decorative applications. S4S lumber is usually sold in standard lengths and can be easily cut and shaped to fit the specific requirements of a project.