(A) The term
FIREPROOF CONSTRUCTION as used in this chapter shall mean a building in which all the parts that carry loads or resist strains, and all exterior walls and all interior walls or partitions and all stairways and elevator enclosures, are made of incombustible material, and in which all metallic structural members are protected against the effects of fire by being embedded in a material which shall be entirely incombustible and a slow heat conductor. If the metal framework of the roof is not less than 20 feet above any floor or balcony, fireproofing of members of the roof framework may be omitted. If the metal framework of a roof is more than 18 feet and less than 25 feet above any floor or balcony, the roof framework may be protected by a suspended ceiling of metal lath and portland cement plaster not less than one inch thick.
(B) The fireproof covering on columns shall not be less than two inches thick if of concrete or gunite, or three inches thick if of other approved material; on girders, not less than two inches thick; or other structural parts not less than 1½ inches thick. The thickness shall be outside the extreme edges of the structural members.
(C) The following building materials, systems, units and forms of construction, assembled and constructed as hereinafter required shall be accepted as fireproof construction:
(1) Plain or reinforced concrete.
(2) Reinforced gunite.
(3) Precast reinforced concrete units.
(4) Hollow or solid concrete masonry units.
(5) Brick (clay, sand-lime or concrete).
(6) Plain or reinforced gypsum.
(7) Precast reinforced gypsum units.
(8) Hollow or solid gypsum blocks.
(9) Hollow clay tile.
(10) Metal lath and portland cement plaster.
(D) The order in which the foregoing materials are placed on the list is not to be construed as indicating their relative fireproof qualities.
(E) All fire-resistive construction laid in units or blocks, such as brick and hollow or concrete or clay tile, shall be solidly bedded and laid in portland cement or cement-lime mortar as defined herein on mortar, and shall be thoroughly bonded together by means of broken joints in alternate courses, or by sufficient metal ties or bands, provided, however, that gypsum products shall be laid in gypsum mortar.
('72 Code, § 151.022) Penalty, see § 10.99