February 15, 2016 Discharge Criteria for Car Stacker We have a parking garage that is approximately 15 ft high with a concrete deck and structural beams up to 24 in. depth forming bays of approximately 14 ft by 10 ft. The parking a garage has a series of car hoists to allow for double occupancy of vehicles being stacked one over another. We are trying to position the sprinklers to avoid clearance issues. What is the occupancy classification for this application?" We have reviewed NFPA 13, 2013 edition that you indicated as the applicable standard as well as the 2016 edition. Our informal interpretation is that the occupancy classification is Extra Hazard (Group 2). This was specifically addressed in the 2016 edition of the NFPA 13 standard. The 2013 edition does not address car stackers. New annex A.5.4.2 for Extra Hazard (Group 2) occupancies includes a new item Number (9) - Car stackers and car lift systems with 2 cars stacked vertically. Car stackers are becoming more common and were added to the newer standard. This makes sense since Extra Hazard (Group 2) addresses occupancies where shielding of combustibles is extensive. Clearance issues for fire sprinklers can occur for garage parking. The base requirement is Section 8.6.6.1 that indicates that the clearance between the deflector and the top of the storage shall be 18 in. or greater. There are times where that is impractical where additional sprinklers have to be provided. This would require sprinklers to be placed on the four corners of the vehicle. Annex material A.8.5.6.1 addresses this clearance issue that states, "The 18 in. clearance does not apply to vehicles in concrete parking structures." Since that is located in Section 8.5 General, this applies to all sprinkler types. Parking garages with low height ceilings and piping runs with dry pipe systems create clearance issues for the sprinklers even without car stackers. This usually involves higher vehicles such as large SUVs and vans. Even if the vehicle locations are initially specified and sprinklers are placed accordingly, the striped parking locations can be moved at a later date and impacting the sprinkler clearances. This application has robust concrete construction and considered fire resistive. Thus, damage to the structure is not likely with sprinkler protection. The beams in this structure also create bays that will aid in activation of the sprinklers and contain the heat plume. The sprinkler system should be able to cool upper layer gas temperatures, prevent flashover, and control the fire. Sprinkler systems are designed to control the fire and allow time for the responding fire service to finish the job. Since stacked cars is not specifically addressed by the standard in effect, this is worth discussing with the AHJ. As indicated by Section 1.5 Equivalency, alternative arrangements are acceptable provided that the level of safety is not reduced. There is no better source for supporting equivalency than a newer edition of the same installation standard.
Technical Update is prepared by the Technical Services Dept. of the AFSA: Vice President of Engineering and Technical Services Roland Huggins, a PE registered in fire protection engineering; Phill Brown, a NICET IV certified automatic sprinkler technician and NFPA Certified Fire Protection Specialist (CFPS) and Tom Wellen, a PE registered in fire protection engineering. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright 2016, American Fire Sprinkler Association. All Rights Reserved Training Calendar AFSA Beginning Fire Sprinkler System Planning School 2016 Schedule April 4 - 15, 2016 May 16 - 27, 2016 July 18 - 29, 2016 Oct. 3 - 14, 2016 For more info, call: 214-349-5965 ext. 132 American Fire Sprinkler Association | 12750 Merit Drive, Suite 350 | Dallas | TX | 75251
