The Holy Grail of Rooftop Amenities: How to Maximize Space and Minimize Occupant Load
By Austin Regan
Once the exclusive domain of air conditioning equipment and pigeon coops, building rooftops are now prized amenities. Developers market their buildings based on the views from outdoor spaces and the amenities those spaces hold. While a usable roof can increase the value of a development and offer greater pleasure for building tenants, the NYC roof deck code can often present challenges to designers.
Occupant Loads
Buildings that are not high-rises and have large footprints may have the potential for large recreational roofs. However, the Department of Buildings (DOB) may not allow use of the entire roof space. Once you decide to use the rooftop, the DOB assigns an occupancy and an occupant load to that space. A minimum occupant load is established, based on square footage. Then, the building code assigns maximum square feet per person, based on BC Table 1004.1.2. The problem arises because the table does not have a factor specific to these outdoor amenity spaces. Without a clear category, DOB examiners default to 15 s.f./person, which corresponds to unconcentrated tables and chairs.
Using this standard, the occupant load can quickly grow to hundreds of people, which raises egress concerns. For instance, a residential building under 125 feet is permitted to have 36” wide stairs, as opposed to a 44” standard stair width, per BC 1009.1 Exception 1.2, but this exception limits each stair to a maximum occupant load of 30 people. Thus, a standard two-stair building can only have an amenity area of 900 s.f. (60 occupants x 15 s.f.)
The designer and developer may opt for 44” stairs, which increases the maximum occupant load to almost 300 people and allows more than 4,000 s.f. of amenity space. However, developers often want to limit the official occupant load to avoid creating a Place of Assembly (PA), required for any space that holds 75 or more people. While typically not onerous from a code compliance standpoint, PAs require emergency lighting; these spaces are also subject to an annual city permit fee, as well as yearly FDNY inspections. In addition, PA plans show specific seating arrangements. Any deviation from approved seating plans can incur FDNY violations. Hence, PAs limit the developer’s freedom to modify furniture or landscaping on the roof.
A Balancing Act
Designers have tried many ways to limit occupant load, while expanding square footage of the rooftop amenity space. Often times, this is when a NYC building permit expediter is called in to help provide guidance.
Such tactics include creating planting areas and claiming no occupancy along circulation paths. While DOB examiners formerly worked with designers on these concepts, our recent experience has shown they are allowing less leeway. Where once they would accept a 6” curb to distinguish planting areas from occupied space, examiners now ask for three-foot fences and insist that circulation paths count toward occupant load calculations.
Another approach involves designating roof areas as exercise spaces, which are calculated at 50 s.f./person, per Table 1004.1.2. While the idea seems clever, some plan examiners respond by citing BC 1509.8.1. This section requires 10-foot-high fences for roofs used “for recreational purposes.”
Stated Occupancies
Because of these situations, approval of rooftop amenity spaces depends increasingly upon obtaining a stated occupancy determination. Per BC 1004.1.4, the commissioner can approve a lower occupant load than what is calculated per the table. On smaller buildings with a few dozen dwelling units, one can argue that multiple people from every apartment in the building would have to be on the roof simultaneously to achieve the maximum occupant load. Larger buildings with hundreds of dwelling units will likely have to create a Place of Assembly, but may still wish to limit their occupant load to avoid additional required stairwells.
Since rooftop spaces can add significant value to a property, developers will insist on creating them. Designers in turn should prepare their clients for how that space will affect the design and operation of the building.