Midtown South-Flatiron-Union Square: an elevator-building market
The city folds the Flatiron district into a wider official area called Midtown South-Flatiron-Union Square, and every housing figure on this page is that area's. PLUTO, the city's tax-lot file, counts 21,029 residential units on 502 lots in Midtown South-Flatiron-Union Square. Condo buildings hold 39.6% of them, elevator rentals 35.2%, co-ops 17.1%, mixed-use and other buildings 5.3% and walk-ups 2.7%. Two- and three-family houses round to 0.0%, and the profile lists no one-family row. Just under half the units, 49.0%, are in buildings from 1980 on; 40.1% predate 1940 and 11.0% date from 1940 through 1979.
The area stretches past the Flatiron blocks, with station points reaching 34 St-Herald Sq and 34 St-Penn Station. According to the MTA station dataset, stations inside it on 23rd and 28th Streets include Broadway on the R/W trains, Sixth Avenue on the F/M trains and Park Avenue South on the 6 train. The 14 St-Union Sq complex is split: its 4/5/6 and N/Q/R/W platforms fall in this area, and its L platform in the Greenwich Village area.
Two districts, from Sixth Avenue to Madison Square
The Ladies' Mile Historic District, designated May 2, 1989, begins at Sixth Avenue and West 23rd Street; it lies mainly in this official area and extends into Chelsea-Hudson Yards. The Madison Square North Historic District, designated June 26, 2001, begins at the northwest corner of Fifth Avenue and West 25th Street, and its boundary text names West 26th Street and East 26th Street. Exterior changes to buildings in both districts go through the Landmarks Preservation Commission.
Three records for a tall building
With so much of the stock in elevator buildings, three city programs carry the building's story.
The facade filing
DOB's facade inspection program covers properties higher than six stories. Every five years a Qualified Exterior Wall Inspector, who must be a New York State-licensed engineer or architect, examines the exterior walls and appurtenances and files a technical report. Sub-cycles follow the last digit of the tax block number, and DOB's FISP Universe Map shows which facades are subject and in which cycle. Each report places the facade in one of three conditions:
- Safe: no repair needed, and not expected to become unsafe in the next five years.
- SWARMP: safe now, but needing repairs or maintenance within five years; if not corrected by the next inspection, it must be reported as unsafe.
- Unsafe: hazardous to people or property.
Sidewalk sheds go up when hazardous conditions are found. A SWARMP or Unsafe filing means facade work lies ahead; ask the board how it will be paid for.
Elevators
DOB's elevator compliance rules require each elevator to be inspected and tested twice a year, through an annual periodic visual inspection and an annual Category 1 no-load safety test, with a Category 5 test every five years. Defects found on the periodic inspection or the Category 1 test must be corrected within 90 days. Ask for the most recent results and any defect still open.
Emissions and the energy grade
Local Law 97 sets emissions limits for most buildings over 25,000 gross square feet, for two or more buildings on one tax lot that together exceed 50,000, and for two or more condo buildings under one board that together exceed 50,000. Limits began in 2024 and tighten in 2030, and owners report each year by May 1, certified by a registered design professional; the LL97 page links DOB's covered-buildings list. Separately, the benchmarking program grades buildings on their ENERGY STAR score: A for 85 or higher, B for 70 to under 85, C for 55 to under 70, D under 55, F for not submitting, and N for exempt or not covered. The label goes up near each public entrance within 30 days after October 1. Larger buildings, over 50,000 gross square feet, also owe an energy audit and retro-commissioning every ten years under Local Law 87, with the report due in the year matching the last digit of the tax block.
Inside the unit
A condo buyer owns the apartment itself plus a share of the common elements, which the condo board runs. For a newer building, the offering plan's amendments in the Attorney General's Offering Plan Database record changes the sponsor has disclosed since the plan was filed. The walkthrough stays inside the apartment: heating and cooling equipment serving the unit and how it was installed, windows and their seals, signs of leaks at terraces or setbacks, the electrical panel, plumbing fixtures and drains, and dryer and bath exhaust. In a converted pre-war loft or office building, ceilings and window walls get extra attention. The facade, roof, elevators, amenity floors and the board's budget are outside its reach.
Flood maps are revised over time, and FEMA's zones do not capture stormwater or basement flooding; check the building's address at the FEMA Map Service Center.
On a Ladies' Mile or Madison Square North block, repairs that a FISP report calls for on a designated building can also need a commission permit, so reading the two records side by side shows what exterior work is already in motion.