Four edges, and the order the blocks filled in
The Landmarks Preservation Commission gives Park Slope four edges: "bounded by Flatbush Avenue to the north, 15th Street to the south, Fourth Avenue to the west, and Prospect Park West to the east" (designation report LP-2443). By the same report, the southwestern blocks were developed by 1869 while the eastern part "remained sparsely populated until the 1880s". Prospect Park opened in 1871, and wide-scale building followed in the late 1870s and early 1880s: mansions on Prospect Park West, 8th Avenue and Plaza Street, row houses on the side streets, and "more modest row houses and flats buildings, particularly below 11th Street". Two Italianate frame houses, 457 12th Street and 565 11th Street, appear to predate 1869; together with 420 13th Street, LPC calls them the oldest buildings in the extension district.
Read the style and you know the facade material
The original designation report, LP-0709 of July 17, 1973, pairs styles with materials. In paraphrase, French Second Empire, neo-Grec and Romanesque Revival fronts generally used brownstone. Queen Anne houses used face brick with narrow joints, colored mortar and terra cotta. The later neo-Renaissance and neo-Classical rows favored limestone, or light brick with limestone trim. Bracketed cornices were generally wood.
How each ages is general building science.
- Brownstone is a soft sandstone applied as a facing. Water behind the face scales it off in sheets, first at the stoop, sills and door hood. LPC counts over 200 neo-Grec row houses and flats buildings in the Extension, its most popular style, and the 1973 report pairs neo-Grec with brownstone; pairing the two is our reading.
- Wood cornices often conceal a built-in gutter. Rot starts on the roof side, so we check from the roof.
- Narrow-joint face brick is damaged by repointing in hard modern mortar; we look for spalled edges beside fresh joints.
- Limestone wears slowly, but iron lintels and anchors set in it rust, swell and crack the stone.
Indoors, a row house of the late 1870s or 1880s can still have some first-generation systems, and flats buildings of the same era repeat them floor by floor: a cast-iron waste stack, galvanized supply branches narrowed by rust, a steam boiler venting into a party-wall chimney, and sometimes live knob-and-tube wiring above the top-floor ceiling.
1973, 2012, 2016: which district is the house in?
- The Park Slope Historic District dates from 1973. City Planning counts 44 blocks (DCP's Park Slope rezoning summary).
- The Extension, designated April 17, 2012, added approximately 600 buildings immediately to the west and south (LP-2443).
- Extension II, designated April 12, 2016, added 292 buildings next to the northern part of the 1973 district (LP-2558).
Not every block is inside one of the three. Before pricing new windows or a rebuilt stoop, find out which side of the line the house is on; exterior work inside a district generally needs a Landmarks permit.
How much house the 2003 zoning allows
The City Council adopted a 110-block rezoning of Park Slope in Community District 6 on April 30, 2003. R6B and R7B contextual districts were mapped over more than 70% of the area. R6B sets a floor area ratio of 2.0, a 40-foot street wall and a 50-foot height limit. Fourth Avenue was mapped R8A instead: a ratio of 6.02, a base of up to 85 feet and a 120-foot limit. Our reading: this is why side streets kept their row-house scale while Fourth Avenue was opened to buildings of up to 120 feet.
In a Fourth Avenue apartment, a unit inspection covers what is inside your walls. For a tall Fourth Avenue building, facade inspection filings and Local Law 97 emissions status come from the building's public records and board documents, not from inside one apartment.
South of 15th Street the rules change
LPC stops Park Slope at 15th Street, and City Planning starts South Park Slope there: a 50-block area "generally bounded by 15th Street on the north", in Community District 7, not 6. It was rezoned on November 16, 2005; the summary says the area was built "primarily as worker housing for the industries along the Sunset Park waterfront, the Gowanus Canal and Green-Wood Cemetery". Under the Department of Buildings' Local Law 152 schedule, District 6 buildings are due during 2026 and again in 2030, while District 7 had its turn in 2025 and returns in 2029. The schedule does not apply to one- and two-family houses.
Past Fourth Avenue: the Gowanus Canal
Fourth Avenue is LPC's western edge; the canal is further west, in Gowanus. The U.S. Environmental Protection Agency placed the canal on the Superfund list on March 2, 2010 (EPA release). The city's post-Sandy report says floodwaters "overtopped the Canal's bulkheads, inundating industrial and residential buildings surrounding the Canal" (SIRR, chapter 14). That sentence is about blocks around the canal; it does not name Park Slope.
To place a particular lot, start with the city's flood map pages, then confirm on the FEMA Map Service Center. In any cellar we look for a backwater valve, a sump and tide lines.
The housing count: ZIPs 11215 and 11217
Roughly 32,323 housing units, 72.0% of them in structures built before 1940 and only 5.6% built since 2010: that is ZIP code tabulation area 11215 in the Census Bureau's 2020–2024 American Community Survey (table B25034). No ZIP follows the four edges above: the north end falls in ZIP 11217, shared with other neighborhoods, where 52.2% of units are pre-1940 and 21.4% date from 2010 or later (same table for 11217). By size in 11215, 13.1% of units are in two-unit houses and 22.4% in three- and four-unit buildings (table B25024).
Stations and booking
The MTA station list puts F and G trains at 7 Av, 15 St–Prospect Park and 4 Av–9 St, R trains at Union St and Prospect Av, and 2 and 3 trains at Bergen St and Grand Army Plaza.
A one-family brownstone falls under general home inspections, a house with rental floors under multi-family. Tell us the address and unit count. Coverage is from East New York, the walkthrough in English or Bangla, the written report that same evening.