Establishments engaged in selling primarily lumber, or lumber and a general line of building materials, to the general public. While these establishments may sell primarily to construction contractors, they are known as retail in the trade. The lumber which they sell may include rough and dressed lumber, flooring, molding, doors, sashes, frames, and other millwork. The building materials may include roofing, siding, shingles, wallboard, paint, brick, tile, cement, sand, gravel, and other building materials and supplies. Hardware is often an important line sold by retail lumber and building materials dealers. Establishments which do not sell to the general public and those which are known in the trade as wholesale are classified in Wholesale Trade, Industry Group 503.