In the construction or in the repairing, alteration, or removal of any structures, any scaffolding or staging, swung or suspended from any overhead support and more than twenty feet from the ground or floor, shall have, where practicable, a safety rail properly bolted, secured, and braced and rising at least thirty-four inches above the floor or main portion of the scaffolding or staging and extending along the entire outside length and along the ends thereof.  Also, such scaffolding or staging shall be so fastened as to prevent it from swaying from the building or structure.