Design 2147 CEO Sisto Martello recently had the opportunity to speak with Tony Agati, Code and Zoning Specialist at Design 2147, Ltd, about the latest developments in office-to-residential conversions. Here are some of the important takeaways from the conversation.
Q. When a developer takes on an office-to-residential conversion, what do you think are the biggest obstacles they face in creating apartments?
A. Most existing office buildings constructed prior to 1961 cover nearly the entire lot, and the ability to provide sufficient legal natural light and ventilation to new apartments is definitely the most difficult obstacle. Under the current regulations, you would be required to tear down large portions of the existing building to provide adequate separation from lot lines or to create new courts of 30’ x 40’ in area just to be able to bring light and air into the new apartments. The extensive demolition that is often required is both expensive and onerous, especially considering the level of site safety involved while working in a dense urban setting like NYC.
Q. For mid-block office buildings, an inner court will need to be created to create light and air for habitable rooms. What obstacles does this create for structural engineers and architects?
A. An inner court of no less than 1200sf with a minimum dimension of 30’ is required to serve any legally required apartment window. Existing office buildings currently need to be able to survive extensive demolition in order to provide these courts, and this can lead to issues with structural stability, especially in tall slender buildings where a majority of the core is designed to resist lateral loads.
Q. Assuming the core of the building will need to be demoed to create an inner court for light and air, what are you seeing as a method for the demolition and reconstruction?
A. Such extensive demolition of a building core often results in the reconstruction of a new stair and elevator core located elsewhere in the building. The new core is constructed and is used to retain the structural stability of the building while the old core is removed.
Q. A developer who is currently in the middle of an office-to-residential conversion said that when they build new buildings in Manhattan, their biggest cost exposure is digging and installing the foundation. I understand you are currently working on a project that is an office-to-residential conversion. Would you agree with the developer’s assessment of exposure? What other challenges offer the most exposure in your opinion?
A. Yes, I’d agree with the developer. Many new building developments in the City have difficult and complex foundation systems due to the widely varied soil strata. Whether drilling into or blasting rock, or remediation of contaminated soils, or drilling and grouting caissons in silty soils, the foundations system for any high-rise building in the city will be both complex and expensive. Many times, underpinning of adjacent building foundations also adds to the cost and complexity. Coordination and negotiation with adjacent property owners for construction access and potential light and air easements, where required light and air is being sought from above adjacent lower buildings, can be lengthy and expensive.
Q. What makes office-to-residential conversions worth the investment in cost and labor?
A. With the current abundance of available empty office buildings and the need and desire for more options for localized housing, including affordable options, it is simply more cost-effective to adaptively reuse an existing building rather than to demolish it completely and then construct an entirely new building on a site. Not only are there cost benefits but also time savings with the process.
Q. Do you see office-to-residential conversion as a net positive for New York City?
A. Yes, absolutely. Adaptively reusing and converting an existing office building to residences not only increases the available localized housing stock but also decreases the number of unused empty office buildings, all without the need for complete removal of the existing buildings. This allows us to retain the existing building’s character and history. Once a building is demolished to the ground, it is gone forever. New apartments will bring new vitality to areas of the city that are currently eerily silent and vacated because they are filled with empty office buildings.
