Porticos, entranceways, storm enclosures, bay windows, oriel windows, porches, or similar appendages may be constructed of combustible materials or assemblies on buildings of construction class II-E to an unlimited extent, and on buildings of construction classes II-A, II-B, II-C, and II-D under all of the following conditions:
(a) The building is classified in occupancy group J-2 or J-3.
(b) The building is not more than three stories or forty feet high.
(c) The appendage has an exterior separation on all exposed sides of at least fifteen feet, measured from the outermost surface of the appendage.
(d) The appendage is so constructed that its removal or destruction will not reduce the structural stability or fire resistive integrity of the building.
(e) The vertical surface area of the combustible portions of the appendage, including any exterior trim, is not more than ten percent of the total wall area (windows excluded) of the building.
(f) The appendage has a superficial roof area not exceeding one hundred fifty square feet and is included in the area limitations of table 4-1 and 4-2 for the entire building.
(g) The appendage is not higher than the sills of the second story windows.
(h) The roof of the appendage has a class A roof covering.
(i) The soffit or ceiling covering the combustible roof framing of the appendage has a one hour fire-resistance rating.
(j) The requirements of subdivisions (h) and (i) of this section shall not apply in the case of roofs or awnings over patios or entrance platforms where the area of vertical exposure of the patios or platforms to the outdoors is equal to at least that of the patio or platform area. Plastic shall be slow burning; canvas or other fabric shall be noncombustible or flameproofed in accordance with the provisions of title fifteen of the administrative code.