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NFPA 13R & Garages Policy
NFPA 13R may be used for hotels, apartments & dormitories where occupancy is no more than 4 stories above grade. Occupancy may also be 1 story below grade. It is acceptable to still use NFPA 13R when the building has a 5th story with no occupancy on that story, such as a mechanical equipment penthouse. But what is one to do when there is a garage area below the residential portion?
There are several possible scenarios where vehicle parking is below the residential units:
1. Separate garage space for each tenant: NFPA 13R may be used when the lower level is a parking garage where there is a separate garage for each tenant. This is clearly incidental according to the 2010 edition, section 7.3.3 and can be treated as residential space in terms of design. The heads can be residential heads at .05 gpm/sq ft, or extended coverage heads at .1 gpm/sq ft, or quick-response heads at .05 gpm/sq ft, (but in reality with K= 5.6 and needing at least 7 psi, at 15’ x 15’ spacing you can only get down to a density of .066 gpm/sq ft.). Coverage is not required below overhead garage doors.
2. The garage is an open common area for all tenants: When the building qualifies for 13R according to the first paragraph above and has a garage level that is intended for use by the residents only but the garage is an open common area then consider which of the two following arrangements apply:
a. When the parking spaces are limited to 1 line of spaces such that no more than 4 fire sprinkler heads cover the area of each vehicle then 13R may still be used. (The principle used here is that when the hazard is limited to a linear space such as a corridor, then the fire is more readily contained by the fire sprinkler coverage. Section 1.4 is used for accepting an alternate arrangement.) In this case however the heads will have to be quick-response type using a density of .15 gpm/sq ft at a maximum of 130 sq ft per head. You may use a 4-head calc for the garage area, but any interstitial floor/ceiling space between the garage and the residential portion is required to have fire sprinkler coverage as well. Coverage is required below overhead garage doors. This is basically covered according to NFPA 13, except for the number of heads to calculate.
b. When the parking spaces form more than 1 line of spaces with no fire separations between vehicles then our office would regard this as a commercial hazard rather than anything incidental to residential. A "bulk area" of vehicle parking must be covered according to NFPA 13, including any ceiling/floor interstitial space between the garage and the residential section. Hydraulic calculations for the garage portion will then be according to NFPA 13. Coverage is required below overhead garage doors. This arrangement is most commonly seen in large hotels.
3. The garage level is also available for non-residents: When the building qualifies for 13R according to the first paragraph above but has a garage level that is also available for non-residents then NFPA 13 must be used for the entire building.
An exception is when there is a minimum of 2-hour fire separation between the garage and the residential portion with structural integrity such as a concrete deck, plus separate required exiting for each portion. In that case NFPA 13R can be used for the residential portion but NFPA 13 will have to be the standard for the garage portion, including any ceiling/floor interstitial space between the garage and the residential section. Hydraulic calculations for the garage portion will then be according to NFPA 13. Additional coverage is required below overhead garage doors. Concealed combustible areas within the 13R portion will not need to have fire sprinkler protection. This includes attics, however the NFPA 101 Life Safety Code does require fire drafts in attics every 3,000 sq ft, or fire sprinkler coverage of the attic. If the fire sprinkler coverage option is used, then you can use quick response heads at a 4-head calc at .1 gpm/sq ft or at the listing of the head.
[First posted 10-10-12.]
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