A Close Look at Big City Back Porches: Balconies, Terraces and Rooftops
By : Adam R. McManus
By and large, private outdoor real estate such as balconies, terraces and rooftops command a premium in most inner cities. Add on views that frame monuments, cityscapes, bridges and natural vistas, and their values rise accordingly. These building elements are outdoor portals to the best vantage points in high density urban areas. There are many reasons to enhance the exterior spaces on a building, and it’s valuable for owners and occupants to know the investment potential for underutilized exterior building spaces. But, where do you start?
Per square foot, a balcony or terrace equates to as much as 50% of the per square foot cost of the adjacent living space, according to a recent article by Paul Reynolds.This private outdoor piece of property may be a garden spot with planters or an auxiliary gathering space with seating. An old classic Seinfeld episode featured a main character who created the “Anytown USA” back porch . The problem was that his “back porch” was actually space he converted in the hallway of his apartment building. This creative spoof on NYC life highlights our common desire for outdoor personal space.
We will focus on three important features that can make this type of exterior space code compliant, user friendly and aesthetically appealing. Whether they are cantilevered from a façade, perched at the rooftop or set back over an interior space, all exterior building spaces will require structurally engineered decks/floors to handle load capacity, guardrail systems and pedestrian walking surfaces that will protect the waterproofing system from wear and tear.
Owners should be aware of the structural load limitations of a terrace, balcony or roof system, and the multiple factors that affect the overall structural loads once these spaces are occupied. These fixed loads may include integrated drop ceilings, pipes and furniture to name a few. Occupants in the space contribute to the live load, which is a dynamic force compared with the permanent structure. Each outdoor space should have a known limit for pedestrian usage. This will help ensure that the structure is not overloaded and placing occupants at risk.
Elevated decks such as wood pavers and concrete tiles can be customized to float above a waterproofing system with pedestals, allowing a uniform and level walking surface for pedestrians. If the waterproofing system is direct-to-structural deck, the finish for pedestrian traffic may be a paver/tile in a mortar setting bed, or a fluid applied finish coat with broadcast aggregate embedded for slip resistance. The finished height of a pedestrian surface directly impacts the required height of perimeter guardrails or building walls.
Railing system options for outdoor spaces are extensive. A railing may promote light transference and greater visibility in lieu of a solid perimeter wall. Railing systems can be manufactured from glass and steel, cast iron, steel cable, stone balustrade and banisters, wood, composite, fiberglass and many other variations of materials. Whether a railing or solid parapet serves as a guardrail, the current NYC DOB minimum code height requirement of 42” above the finished surface is the same.
There are financial tradeoffs to consider when converting or enhancing outdoor areas such as balconies, terraces and rooftops. Unknown requirements with structural loads, pedestrian surfaces and guardrails are three main reasons rooftop conversions and enhancements are indefinitely deferred. For both building shareholders and private owners, there are requirements to keep these spaces safe for pedestrian use, and watertight for the lifespan of the building. Multi-story building owners with the desire to expand their properties’ amenities, along with the money to invest in these endeavors, may find it worthwhile to meet with building occupants. Together, they could dream and plan how to enhance common outdoor space to create that great back porch in the big city