sprinklernotes
Omitting Sprinklers from Ceiling Heights Greater than 55 ft
You have asked the following questions: “We have a university that plans to build a large indoor sports arena on its campus. Some are of the opinion that sprinklers are not required over the sports floor area where the ceiling/roof height is greater than 55 ft while there are others of the opinion that sprinklers are required. The roof structure of the building is all steel. Presently there are standpipes planned and a fire pump. Also, the university plans to hold graduation ceremonies on the main floor with approximately 1000 seating capacity on the floor. Are sprinklers allowed to be omitted from the ceiling above the sports floor area?” We have reviewed NFPA 13, 2013 edition that you indicated as the applicable standard as well as the 2015 edition of the International Building Code (IBC) and the 2015 edition of NFPA 101, the Life Safety Code (LSC). Our informal interpretation is that the omission of protection is not allowed except for very restricted applications. The starting point is that NFPA 13 does not allow the omission of protection based on high ceilings. Although fire modeling on sprinkler activation (DETACT) shows a very large fire (28 megawatts) is needed to activate a sprinkler in a 100-ft ceiling, FM Global has done full scale testing that shows these models are excessively conservative for higher ceilings. As such, it is recognized that there is value in having sprinkler protection in relatively high ceilings. Since the NFPA standards do not recognize high ceilings as an issue, one must look at the codes to see if any such allowances exist. Interestingly, the IBC allows the omission of sprinklers from the ceiling of the atriums with ceilings greater than 55 ft (see section 404, exception No. 2). It also states this is allowed only when the area is restricted to low fire hazard uses. These two characteristics equally apply to the floor area for a sports arena, but there are no separation requirements applicable to an arena, so there is a difference. Despite that, section 507 Exception No. 2 of the IBC has an allowance for omitting sprinklers for areas of indoor participant sports (that is not triggered by ceiling height). This section addresses buildings with unlimited area. It requires sprinklers throughout the building then provides an exception for participant sports. It is limited to buildings no more than one story above grade plane and has exiting and fire alarm requirements. Since allowed in a building with unlimited area, it is reasonable to apply it to a standard building. Whether or not the height limit would still apply would depend on the AHJ. This allowance is for just A-4 uses, so it would not apply to your situation due to the other functions. There is another code, the LSC, which does allow an assembly occupancy used for contest, performance, or entertainment to omit the sprinklers over the floor area when the ceiling is greater than 50 ft. As the name implies, though, this code addresses just life safety and is less conservative than the IBC or NFPA 13. The LSC could, though, take precedence. This would occur when the building code does not require sprinkler protection, and it is required by the LSC. When both require protection, the most conservative of the two is required to be applied. It is also worth stating that with this area being used for other activities, like graduation ceremonies, the occupant load will be far greater than that seen by a standard A-4 use. The only way to omit sprinklers from this location is to pursue an equivalency and obtain written acceptance by the AHJ.
