California Labor Code
As used in this article, "building" means any multifloor building, other than structural steel framed building, more than two stories high in the course of construction.
Every building shall have the joists, beams, or girders of floors below the floor or level where any work is being done, or about to be done, covered with flooring laid close together, or with other suitable material to protect workmen engaged in such building from falling through joists or girders, and from falling substances, whereby life or safety is endangered.
Every building which is of reinforced concrete construction, with reinforced concrete floors, shall have the floor filled in, either with forms or concrete, on each floor before the commencement of work upon the walls of the second floor above or the commencement of work upon the floor of the next floor above.
Every building having wooden floors other than a steel frame building shall have the underflooring, if double flooring is to be used, laid on each floor within the time prescribed above for reinforced concrete floors. Where single wooden floors are to be used, each floor shall be planked over within the time prescribed above for reinforced concrete floors.
If a span of a floor on a building exceeds 13 feet, an intermediate beam shall be used to support the temporary flooring, but spans not to exceed 16 feet may be covered by three-inch planks without an intermediate beam. The intermediate beam shall be of a sufficient strength to sustain a live load of 50 pounds per square foot of the area supported.
If building operations are suspended and the temporary flooring required by this article is removed, the building shall be replanked upon the resumption of work so that every man at work has a covered floor not more than two stories below.
Where a building is being constructed in sections each section constitutes a building for the purpose of this article.
Planked floors on buildings shall be tightly laid together of proper thickness, grade and span to carry the working load; such working load to be assumed as at least 25 pounds per square foot.
Safety belts and nets shall be required in accordance with Article 24 (commencing with Section 1669) of subchapter 4 of Chapter 4 of Part 1 of Title 8 of the California Administrative Code, Construction Safety Orders of the Division of Occupational Safety and Health.
No person shall proceed with any work assigned to or undertaken by him, or require or permit any other person to proceed with work assigned to or undertaken by either, unless the planking or nets required by this article are in place. Violation of this section is a misdemeanor.
The Division of Occupational Safety and Health shall enforce this article.