Okla. Stat. tit. 40, § 40-175: Temporary floorings in steel frame buildings

If in the erection of an iron or steel framed building, the

spaces between the girders or floor beams of any floor are not

filled or covered by the permanent construction of said floors

before another story is added to the building, a close plank

flooring shall be placed and maintained over such spaces, during the

construction of each story, from the time when the beams or girders

are placed in position; but openings protected by a strong hand

railing not less than four (4) feet high may be left through said

floors for the passage of workmen and material.