Lab. Code, § 7325

“Building,” as used in this chapter, means any building three stories or more in height, and whether heretofore constructed or hereafter to be constructed, including commercial buildings of all types, office buildings, apartment houses, hotels and buildings used for manufacturing purposes, but excluding dwelling houses occupied by not more than three families, and excluding all buildings constructed with windows that may be, and are, entirely washed and cleaned from inside the building or from a sitting position on the window sill in the manner provided by safety orders issued, or which may be issued from time to time, by the division.