Par. 1. - Walls may be built in part of iron or steel or with a reinforced concrete or metal framework. In such metal framework the beams and girders shall be riveted to each other at their respective junction points. If columns made of rolled iron or steel are used, their different parts shall be riveted to each other, and the beams and girders resting upon them shall, if possible, have riveted connections to unite them with the columns. If cast iron columns are used, each successive column shall be bolted to the one below it by at least four bolts not less than three fourths of an inch in diameter, and the beams and girders shall be bolted to the columns. At each line of floor or roof beams, lateral connections between the ends of the beams and girders shall be made in such manner as rigidly to connect the beams and girders with each other in the direction of their length.

Skeleton Party Walls

Par. 2. - All party walls of skeleton construction shall have curtain walls of brick, not less than twelve inches thick.

Par. 3. - All outside walls of skeleton construction shall have curtain walls which may be of masonry, terra-cotta, concrete, or reinforced concrete, constructed and supported under such conditions as the commissioner shall prescribe.

Par. 4. - If the metal or other framework is so designed that the enclosing walls do not carry the weight of floors or roof, then the walls shall be of masonry or concrete construction and shall be thoroughly anchored to the iron skeleton, and whenever the weight of such walls rests upon beams or columns, such beams or columns shall be made strong enough in each story to carry the weight of wall resting upon them without reliance upon the walls below them.