§ 27-348 Interior finish.
AC § 27-348
(a)Definition. For the purposes of this section, interior finish shall mean those materials that form the exposed interior surfaces of a building and that are part of or affixed to walls, fixed or folding partitions, ceilings, and other construction elements.
(b)Classification. Interior finish materials shall be classified in accordance with the surface flame-spread rating obtained as prescribed in the provisions of reference standard RS 5-5. Where an interior finish material is comprised of two or more materials laminated, glued, nailed, or otherwise secured together, the test rating for flame spread shall be based upon the composite of the materials in the form in which it will be used in construction. Interior finish materials shall be grouped in the following classes, in accordance with their surface flame spread characteristics: Interior Finish Class Flame-Spread Rating A 0 to 25 B 26 to 75 C 76 to 225 D Over 225 (c) Requirements. Interior finishes and exposed structural or construction materials shall have a flame-spread rating not greater than that designated by the class prescribed for the various occupancy groups in which they are used, as listed in table 5-4. Exceptions to these requirements are: (1) Finish flooring and floor coverings, which are subject to the requirements of section 27-351.
(2)Wall coverings and coatings that are less than 0.036 in total thickness, when applied directly to a noncombustible, or fire-retardant treated wood, substrate.
(3)Exposed structural members and planking in buildings of class II-A construction, which may be left exposed in any room or space, except in exits.
(4)Twenty per cent (20%) of the aggregate wall and ceiling area of any room, space, or corridor required to have a class A or B rating may be finished with materials having a class C rating. This allowance shall include the area of doors, folding partitions, windows, glazing, skylights, luminous ceilings, trim, bases, chair rails, panels, moldings, etc. This exception shall not operate as a waiver of other requirements of this code relating to opening protectives.
(5)When a sprinkler system is provided in any room or space, and is installed in compliance with the construction provisions of subchapter seventeen of this chapter, interior finish materials may be one class higher in flame-spread rating than required by tables 5-4.
(d)Smoke density. No material shall be used for interior finish in the following locations if the material develops smoke in greater density than the rating shown, based upon a test conducted in accordance with the provisions of reference standard RS 5-5. Materials used for interior finish that cover not more than twenty percent of the aggregate wall and ceiling area of any room, space, or corridor shall be exempt from the above requirements. Location or Occupancy Smoke Developed Rating Exits, corridors 25 Occupancy groups H-1 and H-2 50 Rooms in which the net floor area per occupant is ten square feet, or less 100 (e) Toxicity. No material shall be used in any interior location that, upon exposure to fire will produce products of decomposition or combustion that are more toxic in point of concentration than those given off by wood or paper when decomposing or burning under comparable conditions.
(f)Attachment of interior finish.
(1)To be credited with the same rating, interior finish materials that were applied to a substrate when tested shall be applied at the building to an equivalent substrate.
