636 Warren Street

Each of the three buildings has eight apartments on four floors, two per floor. The layout shows up in ACRIS unit designations running 1L and 1R through 4L and 4R at each address. The corner building at 99 Fourth Avenue, which carries the 636 Warren Street address, has somewhat larger upper-floor apartments than its two neighbors, per the Department of Finance roll. At every address the first-floor apartments are the largest on the roll. Whether that extra space is on one level or runs into the cellar or rear yard should be checked against the declaration's floor plans for the specific unit.

The building has no elevator, doorman or garage. There is no commercial space on the Fourth Avenue frontage: PLUTO records the whole building area as residential.

A note on the city's data. PLUTO lists one address, 99 Fourth Avenue, for three buildings. It gives a construction year of 1920 that the Department of Finance contradicts for 23 of the 24 units, and a 1986 alteration year that most likely reflects the sponsor's conversion work. Treat all of these as approximate. The unit count of 24 is correct.

Tax history. The city's J-51 records show a benefit on all 24 units starting in the 1987/88 tax year. It combined a 90 percent abatement with an exemption that was first carried at 12 years and later at 14. The exempt amounts were gone after 2001/02 and the abatement pool was used up in 2002/03. The current exemption roll, 2020/21 through 2026/27, shows no J-51 or 421-a. Apartments pay full Class 2 condominium taxes, apart from personal exemptions some owners hold.

Capital work. The public record here is thin. The only Department of Buildings job in the open-data file for the corner building is a 2011 alteration, and there are none for 101 or 103. Ask the managing agent for the reserve balance, the dates of the last roof and façade work, and any planned or recent assessment. In a building this small, capital work can fall to assessment.

Zoning and air rights. PLUTO maps the lot C4-4D with a maximum residential FAR of 6.02, against the 3.28 that is built. On paper, that leaves a large amount of unused floor area. In practice, redeveloping the site or selling the air rights would need action by the condominium under its declaration and by-laws, with the owners of 24 units and their lenders involved. Treat it as a long-term possibility, not something to add to an apartment's value.

Recent sales

Recent closings at this building, from The Roebling Research Library. Prices are the transfer amounts recorded with the NYC Department of Finance; apartment-level detail is checked against the building’s own file in The Roebling Research Library before publishing.

Market read. Most recent trades (2026 to date) cleared a median $1,412/sf (recorded) across 1 sale. Median listing discount 1.9% from the last ask — a recurring negotiation gap worth pricing into any offer or listing strategy.

Sales sourced from NYC Department of Finance recorded transfers (BBL 3-00937-7501; each condominium apartment is its own tax lot). Apartment-level facts (line, condition, asking-price context) curated and cross-verified in The Roebling Research Library. Not all transactions cross-verify with ACRIS records — sponsor and LLC purchases sometimes record at stipulated values rather than market price; square footage from recorded condo declarations and offering plans.

Confirm which building and which unit. One billing lot covers three buildings, and the unit designations repeat at each address. Match the tax lot, the address and the unit to the declaration before contract.

There is no abatement to lose. The J-51 benefit ran out more than twenty years ago, so the current tax bill is the real one.

Ask for the capital file. Little capital work shows up in the public record. The reserve, recent assessments and the condition of the roof and façade are the main things to check.

Walk-up, and a condominium. There is no board admission process of the kind a co-op has. Confirm with the managing agent whether the declaration gives the board a right of first refusal, and what it says about leasing and pets.

Sell the tenure. A condominium in a prewar walk-up is rare in this part of Brooklyn. Buyers who want an older building without co-op board approval have few choices, and this is one. Confirm subletting and financing rules in the declaration and by-laws.

Price against like-for-like. The right comparables are other condominiums in older walk-up buildings and the small co-ops around them, not the new buildings on Fourth Avenue.

If you're considering 636 Warren Street, also evaluate:

• Baltic Park Slope (613 Baltic Street): the 2017 elevator condominium at the Baltic Street end of the same block
• 11 Sterling Place (Sterling Court): a 1986 Park Slope condominium conversion from the same era
• 100 Sterling Place: a 1990 North Slope condominium with no remaining tax abatement
• 145 Park Place: a North Slope condominium whose J-51 abatement has also fully expired
• The Mill, 376 President Street: a 1988–89 condominium conversion in Carroll Gardens with a similar J-51 history
• 610 Warren Street: a 2017 condominium on the same street, with an active 421-a schedule
• 243 Fourth Avenue (Parlour): a new-construction condominium on the Park Slope stretch of Fourth Avenue
• The Presidential, 759 President Street: a 1984 Park Slope conversion held as a co-op, for buyers comparing tenure