Michael Stern

By Michael Stern, JDS Development Group Every site carries a limit on how much of its own ground a building may stand on, and that limit is settled in plan long before anyone draws a section. Two of our towers answer it in opposite directions, and what separates them is a decision about plan rather than about size. This is written for the developer, the architect and the zoning consultant standing over a constrained lot, deciding a footprint. The footprint is the decision that closes the most doors behind it. 111 West 57th Street is the tallest and most slender residential building in the Western Hemisphere, so it stands on very little ground and takes its area upward. The American Copper Buildings occupy a former Con Edison site as twin towers with open ground held between them. One question about the ground, two answers. What does lot coverage actually measure? Coverage is the portion of a zoning lot that a building would cover when the lot is viewed directly from above. It is ...

By Michael Stern, JDS Development Group The question an architect asks me first about the base of a tower is why so much of it goes to cars. On a site where the rules require parking, the number of spaces is fixed before the plan is drawn, and a number of spaces is a volume of building with a geometry of its own. This is written for the developers, architects and planners who have to decide what the bottom of a building must be before they can decide what it might be. A parking space stops being a number the moment it reaches a drawing. It becomes a stall of a given size, reached by an aisle of a given width, served by a ramp at a slope a car can climb, under a structure with the headroom a vehicle needs and a floor to floor height no apartment would ever ask for. Where the rules require parking, the requirement attaches to the residences on the zoning lot and is written as a count. That count is the first fixed quantity on many sites. Floor area can be moved, massing can be argued...

By Michael Stern, JDS Development Group Photo by Julien Riedel on Unsplash A lot I looked at recently carried a base district designation that anyone could read off the public zoning map in a few seconds. The rules that actually governed what could be built there took a zoning consultant the better part of a month to assemble. The designation was accurate, and it was also the smallest part of the answer. A special district had been drawn over that block, a contextual rule governed the street wall along one frontage, and the lot carried a designation that no district color on any map records. This piece is for developers, architects and land use professionals who have to decide whether a site is worth a full analysis before anyone has paid for one. What the base district on the map actually decides The base district is the layer everyone starts from because it is the layer the map is drawn to show. It sets the broad quantities: how much floor area the lot may hold, what uses are p...

By Michael Stern, JDS Development Group The building code carries a table that sets how tall a building may be and how large its floors may be for each type of construction it allows. Read that table beside the zoning for a site and the smaller number is often the code one, which means the top of the building was decided by a construction document rather than by the envelope rules. I am writing this for developers and architects working on constrained sites in the middling heights, where the two documents disagree and only one of them can be satisfied last. What the Height and Area Tables Actually Govern The code sorts buildings by what they are made of and how well that material is protected from fire. Each type carries a permitted height and a permitted floor area per story, and the use of the building moves those numbers again. Nothing in that table is about light, air, bulk or the street, which is the whole business of the model codes a body like the International Code Council ...

By Michael Stern, JDS Development Group Photo by Wojciech Wyszkowski on Unsplash A zoning district boundary does not stop at a property line. It is drawn on a map at the scale of a neighborhood, and now and then it runs straight through the middle of a single lot, leaving one piece of ground answering to two sets of rules at once. If you develop on constrained urban sites, or you advise the people who do, the split lot is the condition that most often explains why a building on an ordinary looking site came out in an unusual shape. What follows is how that works, in order, because the order is the whole insight. The floor area on such a lot is not computed once. It is computed for each portion, under the rules of the district that portion sits in, and the building is the sum of what those two computations permit. How Floor Area Is Computed on a Split Zoning Lot Start from the ground. The lot is one parcel in the deed and two parcels in the zoning, and the line between them i...

By Michael Stern, JDS Development Group A foundation is completed on a Thursday and the zoning that governs the site changes the following week. The building that foundation was designed for is still legal. The building the new text describes is a different one, and nobody is building it on this lot. This is for developers, land use lawyers and construction managers working on sites where the rules move while the schedule runs. The mechanism that decides the outcome is a recognition, written into zoning itself, of work that has already substantially begun. What it protects is progress in the ground, and what it turns on is a very small number of dates. What Zoning Protects When Construction Has Already Begun A zoning amendment does not reach backward through every project on every lot. Text and maps change constantly, which is ordinary work in the planning profession and a standing condition for anyone developing on a long timeline. A project that has reached a defined stage of ...

By Michael Stern, JDS Development Group Photo by camera obscura on Unsplash A lot on an assembled site can carry floor area that no survey of that lot will ever show. The area arrived from a neighbor, it lives in an instrument filed with the office that keeps the land records, and the only place it can be proved is the record of title. This is written for developers, land use lawyers and underwriting professionals who have to establish how much building a site actually holds before a design exists. On the sites I work on the buildable envelope is assembled rather than found, and the assembly is legal before it is physical. The document that performs it is a recorded declaration, and everything the tower is permitted to be rests on that document being drafted and filed correctly. What a Development Rights Transfer Actually Records A transfer of unused floor area is not a conveyance of land. Nothing about the boundary of either lot changes and both owners keep their parcels. ...

By Michael Stern, JDS Development Group Photo by Sebastian Hages on Unsplash Two lots on the same block each hold floor area they will never use, and a third lot sits between them. That third lot decides whether either of the first two can ever contribute to a tower, because under the general rule floor area moves only between lots that form a single zoning lot, and a zoning lot has to be contiguous. This is written for developers and land use professionals evaluating an assemblage, and for anyone who has looked at a block map and wondered why a small site can hold a tall building while a larger one nearby cannot. What a zoning lot is and why it is the unit that matters Floor area is counted on the zoning lot , a unit the zoning creates for its own purposes, which can be one tax lot or several tax lots treated as one under the rules. The deed map and the zoning map therefore disagree by design. The deed map shows who owns what, the zoning map shows what may be built where, and the...