Sprinklering the top tier of an enclosed parking garage

[NFPAnarc]

The 2021 and newer editions of the IBC require all parking garages to be sprinklered so the conversation can apply to either open or enclosed garages, but the question came from the 2018 IBC.

If you have an S-2 enclosed parking garage that requires sprinkler protection the Chapter 903.2.10 that language reads "...shall be provided throughout the building." If that enclosed parking garage had a fully open top tier would that also require sprinkler protection? Logic would say no since it wouldn't have a roof and sprinklers can't operate without heat collection but that top open tier would still be a part of the building area. Would the language of Chapter 9 require a roof or overhead covering to support those sprinklers, or could sprinklers be omitted? The commentary language of the Chapter 9 requirements say sprinkler protection is required since there is no openness to release hot smoke and gases, but if its the roof top with no overhead structure would that still apply? I couldn't find any language in the rest of IBC Chapter 9, NFPA 88A and 13 tp provide any real direction, but IBC 903.2.1.6 I think would be a good comparison. The presence of roof top occupants doesn't require the roof top to be sprinklered but rather the floors below; following the same approach I don't think the top tier of a parking garage requiring sprinklers would also require sprinklers.

 

[mtlogcabin]

What you are describing is a closed parking with an open parking garage above. You are required to provide stand pipes to the open parking garage and sprinkle the closed parking garage portion.
The code has a section where they can be separate buildings if all the conditions are met.

2018 IBC

510.3 Group S-2 enclosed parking garage with Group S-2 open parking garage above.
A Group S-2 enclosed parking garage with not more than one story above grade plane and located below a Group S-2 open parking garage shall be classified as a separate and distinct building for the purpose of determining the type of construction where all of the following conditions are met:

1. The allowable area of the building shall be such that the sum of the ratios of the actual area divided by the allowable area for each separate occupancy shall not exceed 1.

2. The Group S-2 enclosed parking garage is of Type I or II construction and is at least equal to the fire-resistance requirements of the Group S-2 open parking garage.

3. The height and the number of tiers of the Group S-2 open parking garage shall be limited as specified in Table 406.5.4.

4. The floor assembly separating the Group S-2 enclosed parking garage and Group S-2 open parking garage shall be protected as required for the floor assembly of the Group S-2 enclosed parking garage. Openings between the Group S-2 enclosed parking garage and Group S-2 open parking garage, except exit openings, shall not be required to be protected.

5. The Group S-2 enclosed parking garage is used exclusively for the parking or storage of private motor vehicles, but shall be permitted to contain an office, waiting room and toilet room having a total area of not more than 1,000 square feet (93 m2) and mechanical equipment rooms incidental to the operation of the building.

 

[NFPAnarc]

For the sake of argument lets say we don't meet those requirements, lets say we're a fully above ground 5 tier parking garage in a down town area sandwiched between buildings and can't meet our openness criteria for our lower tiers. The only tier that is open is the top tier and there is no overhead covering or roof, just open to atmosphere.

 

[steveray]

Technically it's not the lack of a roof, but the lack of walls that make it open....

[BG] OPEN PARKING GARAGE. A structure or portion of a structure with the openings as described in Section 406.5.2 on two or more sides that is used for the parking or storage of private motor vehicles as described in Section 406.5.3.

And the throughout the building/ throughout the fire area/ sprinkler whatever needs some work.. But no roof= no fire area= no sprinklers.....generally....

 

[NFPAnarc]

That train of thought makes sense. I think logically most would agree that the code isn't going to force a parking garage to throw a roof on the top tier of a building just to put sprinklers under it. I think that the Chapter 2 definition of open parking garage gives a lot of weight to how to consider the top tier.