sprinklernotes Sprinklers Under Combustible Drive-Through
The following information was provided: I have a drive-through that is over 4-ft wide. It is constructed with steel beams wrapped on the sides and bottom with plywood with 2x12 wood joists 1 ft on center run on top on the beams, then a layer of plywood, then a waterproof membrane, then a metal roof deck. All of the exposed wood around the beams will be covered with a limited-combustible exterior insulation and finish system (EIFS). The EIFS will continue along the bottom of the 2x12s running from soffit to soffit with no insulation between the 2x12s above. The soffits around the steel beams will be filled with insulation or fire stopped to 160 ft3 per section 8.15.1.1. All exposed material is EIFS and metal roof. The AHJ has rejected our drawings and said unless the requirements of NFPA 13 section 8.15.7.1 are met, sprinklers shall be installed under this exterior drive-through. Also, unless the requirements of NFPA 13 section 8.15.1.2 and 8.15.7.3(1) are met for this drive-through for the unsprinklered combustible concealed spaces of this drive-through, these concealed spaces shall be fully sprinklered in accordance with NFPA 13 section 8.15.1.1. You asked the following question: In your opinion, does this drive-through require any sprinklers? In response to your question, we have reviewed NFPA 13, Standard for the Installation of Sprinkler Systems, 2019 edition. Our informal interpretation: Sprinkler protection can be omitted if the EIFS meets the definition of “limited-combustible” and if the combustible concealed space is compartmentalized or filled with noncombustible insulation as described above. Per the pictures and the description, there are actually two components to this issue – a combustible concealed space and an exterior projection. The combustible concealed space is not required to be protected as stated by section 8.15.1.2.5. 8.15.2.3.5 Concealed spaces formed by ceilings attached directly to or within 6 in. (150 mm) of wood joist or similar solid member construction shall not require sprinkler protection. It should be noted that omitting sprinklers in this scenario will require a minimum remote area of 3,000 ft2 for adjacent spaces. For the exterior projection, the requirements of section 8.15.7 will determine the protection under the canopy. 8.15.7* Exterior Projections. 8.15.7.1 Unless the requirements of 8.15.7.2, 8.15.7.3, or 8.15.7.4 are met, sprinklers shall be installed under exterior projections exceeding 4 ft (1.2 m) in width. 8.15.7.2* Sprinklers shall be permitted to be omitted where the exterior canopies, roofs, porte-cocheres, balconies, decks, and similar projections are constructed with materials that are noncombustible, limited-combustible, or fire retardant– treated wood as defined in NFPA 703, or where the projections are constructed utilizing a noncombustible frame, limited-combustibles, or fire retardant–treated wood with an inherently flame-resistant fabric overlay as demonstrated by Test Method 2 in accordance with NFPA 701. 8.15.7.3 Sprinklers shall be permitted to be omitted from below the exterior projections of combustible construction, provided the exposed finish material on the exterior projections are noncombustible, limited-combustible, or fire retardant–treated wood as defined in NFPA 703, and the exterior projections contain only sprinklered concealed spaces or any of the following unsprinklered combustible concealed spaces: (1) Combustible concealed spaces filled entirely with noncombustible insulation (2) Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are directly attached to the bottom of solid wood joists so as to create enclosed joist spaces 160 ft3 (4.5 m3) or less in volume, including space below insulation that is laid directly on top or within the ceiling joists in an otherwise sprinklered attic [see 11.2.3.1.4(4)(d)] (3) Concealed spaces over isolated small exterior projections not exceeding 55 ft2 (5.1 m2) in area 8.15.7.4 Sprinklers shall be permitted to be omitted from exterior exit corridors when the exterior walls of the corridor are at least 50 percent open and when the corridor is entirely of noncombustible construction. The use of the plywood disqualifies the exterior projection as being entirely constructed of noncombustible or limited-combustible materials or fire-retardant-treated lumber, so section 8.15.7.2 and 8.15.7.4 cannot be used. If the EIFS system meets the definition of “limited-combustible,” then sprinklers can be omitted if the channels are compartmentalized into 160 ft3 volumes per 8.15.7.3(2) or if sprinklers are provided within the combustible concealed space per 8.15.7.3.
