Rooftop Additions on Landmark Buildings
A rooftop addition is the most common way a landmark grows, and Michael Stern’s field of landmark conversion meets it constantly, since a conversion that enlarges an old building almost always does so at the top. New York’s rule for it can be stated in three measurable conditions. The history that produced those conditions is a series of hearings, and the two are read together here, rule first.
The rule today
Jorge Fontan, whose office designs these additions on landmark rowhouses, lays out the staff level criteria that let an addition be approved without a hearing: a single additional story, rising no more than eleven feet above the midpoint of the existing roof, and, for a building under seven stories, not visible from the public thoroughfare from any direction; a roof deck can be folded in if it stays within the same limits.5 Meet all three and staff check the application against fixed criteria. Miss any one and it goes to the full Commission, where, in Fontan’s words, the design is judged as a complete composition and may be approved, modified or denied.5
Where the rule is written
The criteria are not folklore. The Commission’s rules page locates them in Title 63 of the Rules of the City of New York, which set out both the agency’s procedures and the standards for work to designated buildings; work meeting the rules gets a staff approval, and work that does not is heard by the Commission.8 One section of that title is headed additions, rooftop and rear yard, and it was among the sections listed for amendment at a hearing the agency scheduled for November 17, 2026.8
The staff level test, in three conditions
- HeightOne additional story, no more than eleven feet above the midpoint of the existing roof.
- VisibilityFor a building under seven stories, not visible from the public thoroughfare from any direction.
- DeckA roof deck may be included if it stays inside the same height and visibility limits.
- DocumentationDrawings and sightline studies that show the addition against the existing building and its neighbours.
- Anything elseGoes to the full Commission, where approval is discretionary and not guaranteed.
The public way as the test
Every version of the rule turns on what a person standing on a public street can see. The test is run with sightline studies and, for larger buildings, with mockups on the roof, and its logic is that designation guards the public’s experience of a building rather than the building as an abstract object. The cases below show the test applied, bent and, once, overruled.
Before the rule: a hotel roof since 1916
Landmark roofs were being built on long before the Commission existed. Pineapple Street notes that the Hotel Bossert in Brooklyn Heights, built in two phases in 1909 and 1912, has carried rooftop additions since 1916, when a restaurant opened above it, with the most recent, a 13th floor and part of a 14th, dating from the end of the 1990s.2 A landmark’s roof is therefore often already layered when an application arrives, and the Commission is judging a new layer against several old ones.
2010: a hearing missed
The procedure has its own lessons. Brownstoner reported the approval of a two story rooftop addition at 30 Washington Street in Dumbo, along with ground floor changes and a canopy, and noted that residents of a neighbouring building turned up to object and were not allowed to speak, because the public hearing where testimony is taken had been held a couple of weeks earlier.1 The record closes before the vote, a point the Certificate of Appropriateness entry explains.
2014: the Apthorp’s three tries
The Historic Districts Council recorded the case that fixed visibility as the governing question for a large individual landmark. A plan to build on the roof of the Apthorp, a full block Renaissance Revival apartment house of 1908, drew heavy opposition at a 2013 hearing because the addition could be seen through the building’s great arches, from inside its courtyard and from as far as half a mile away, and because it enclosed the open pavilions on the roof.6 The third iteration, approved unanimously in August 2014, was a single story with its visibility sharply reduced, and the chair asked for the interior height to come down from eleven feet to ten to lessen what remained visible from Riverside Park; the council regretted the enclosed pavilions and drew the moral that the work of protecting a building does not end at designation.6
The Apthorp, three iterations
- November 2013A first plan heard with wide opposition; visible through the building's grand arches, from its courtyard and from half a mile away, and enclosing the open roof pavilions.
- ObjectionThe council argued the roofscape was a fully conceived Renaissance Revival design that should be kept.
- RevisionCornices and windows that had competed with the building were simplified.
- August 2014A one story addition approved unanimously, its interior height cut from eleven feet to ten to reduce the view from Riverside Park.
- CostThe pavilions were enclosed, a loss the council called regrettable.
2017: a factory roof and an abolitionist’s roof
Two cases that year show the test working in opposite directions. At 50 Hudson Street, a Tribeca factory of 1925, CityRealty reported a two story penthouse approved after the applicants returned with ceilings reduced by six inches, larger window openings, a setback reduced to twelve inches and a new glass corner referencing the building’s design; the chair found it in keeping with the rooftop line and a modern reading of the historic building.4
At 339 West 29th Street, CityLand recorded the rare case where invisibility was not enough. The house, the only documented Underground Railroad stop in the city, had been designated as part of the Lamartine Place district after a Buildings permit for a rooftop enlargement had been issued and then revoked. The owners returned with an addition pulled sixteen feet back from the front wall and sloped twenty degrees, which their sightline studies said no pedestrian could see from any nearby street or from the park to the south, and offered a plaque and a diorama of the 1863 escape across the rooftops.7 The chair answered that this roofline bore a cultural significance which gave her great pause, a colleague called the roof an artifact that set aside the usual visibility considerations, and the vote approved the rear enlargement and the facade work while refusing anything on the roof.7
Two 2017 rooftop cases
| 50 Hudson Street | 339 West 29th Street | |
|---|---|---|
| The building | A 1925 factory, individual review | A rowhouse in the Lamartine Place district |
| The ask | A two story penthouse | A set back fifth story |
| What changed | Ceilings cut six inches, windows enlarged, setback reduced to twelve inches, a glass corner added | Setback of sixteen feet, front wall sloped twenty degrees, no railing |
| Visibility | Judged in keeping with the rooftop line | Invisible from street and park, by the applicant's studies |
| Outcome | Approved | Denied, because the roof carried cultural significance |
2023 to 2026: the rule rewritten
The rule has moved twice since. In 2023, West Side Rag covered amendments widening the range of work staff may approve on their own, mostly solar panels, mechanical equipment and planting, together with Landmark West’s worry that rooftop decisions would increasingly be made out of public sight.3 In 2026 the Bossert case showed the full Commission still applying the older discipline to a large building: after a June hearing at which commissioners found a proposed 15th floor too dominant from the street, the team pulled the 13th and 15th floors inward until, from Remsen Street, the new work receded behind the old cornice, relocated the bulky mechanical equipment to the 12th floor roof and did away with its screen, and won a unanimous vote in September.2 And the November 2026 hearing on Title 63 put the additions section itself back on the table.8
Through every revision one test has held: whether a person on the public way can see the new work, and, where they can, whether it reads as a backdrop to the landmark or as a competitor. A conversion that needs more than the rule allows is making the discretionary case from the start, while the bulk envelope that zoning imposes on the addition is explained under sky exposure.
