(a) All contractors and owners, when constructing buildings where the plans and specifications require the floors to be arched between the beams thereof or where the floors or filling in between the floors are of fireproof material or brickwork, shall complete the flooring or filling in as the building progresses to not less than within 3 tiers of beams below that on which the iron work is being erected.
(b) If the plans and specifications of the buildings do not require filling in between the beams of floors with brick or fireproof material, all contractors for carpenter work, in the course of construction, shall lay the underflooring thereon on each story as the building progresses to not less than within 2 stories below the one to which such building has been erected. Where double floors are not to be used, such contractor shall keep planked over the floor 2 stories below the story where the work is being performed.
(c) If the floor beams are of iron or steel, the contractors for the iron and steel work of buildings in course of construction or the owners of such buildings shall thoroughly plank over the entire tier of iron or steel beams on which the structural iron or steel work is being erected, except such spaces as may be reasonably required for the proper construction of such iron or steel work and for the raising or lowering of materials to be used in the construction of such building or such spaces as may be designated by the plans and specifications for stairways and elevator shafts.
(d) If elevators or elevating machines are used within a building in the course of construction for the purpose of lifting materials to be used in such construction, the contractors or owner shall cause the shafts or openings in each floor to be inclosed or fenced in on all sides by a barrier at least 8 feet in height, except on 2 sides which may be used for taking off and putting on materials, and those sides shall be guarded by an adjustable barrier not less than 3 nor more than 4 feet from the floor and not less than 2 feet from the edge of such shaft or opening.