503901 Prefabricated structures
 50390101 Metal buildings
 50390102 Mobile homes
 50390103 Prefabricated buildings
 50390104 Structural assemblies, prefabricated: non-wood
 50390105 Mobile offices and commercial units
 503902 Glass construction materials
 50390201 Exterior flat glass: plate or window
 50390202 Interior flat glass: plate and window
 503999 Construction materials, not elsewhere classified
 50399901 Air ducts, sheet metal
 50399902 Architectural metalwork
 50399903 Awnings
 50399904 Ceiling systems and products
 50399905 Doors, sliding
 50399906 Eavestroughing, parts and supplies
 50399907 Flue linings
 50399908 Grain storage bins
 50399909 Joists
 50399910 Lockers, construction
 50399911 Septic tanks
 50399912 Soil erosion control fabrics
 50399913 Wire fence, gates, and accessories
 50399914 Metal guardrails