431 Union Street, Brooklyn
Three-family · built c. 1899 · Block 430, Lot 70.
Building permits
- Major Renovation — Residential, filed Aug 19, 2026, estimated cost $1.1M, 2 units in all, 4 stories, described as “Proposed enlargement of the existing 3-story (Basement + 2) to a 4-story (Cellar+4) for a new 2-family house, with general construction work per plan and to comply with new building requirements. Obtain a new Certificate of Occupancy.”
- Alteration, filed Nov 15, 2025, estimated cost $10K, described as “Installation of 300PSF sidewalk shed as per plans. All equipment shall comply with ch #33 of the NYC code 2022. No change in use, occupancy or egress under this application.”
- Alteration, filed Aug 1, 2025, estimated cost $40K, described as “Herewith filing for Facade and Structural repairs plans of existing 2-story building. No changes in use, egress or occupancy”
Property taxes
- Assessment
- $158,460
- 2026–27 tax
- $7,167
- Market value (city estimate)
- $2,641,000
- Taxable value
- $36,116
- Assessed land
- $30,180
- Assessed improvements
- $128,280
Zoning
R6B: floor area ratio 1.14 built, 2.00 allowed by base zoning.
Flood zone
Current FEMA flood map: zone X, minimal flood hazard.
Recent sales
- Jul 23, 2026: $2,450,000, 2,280 sq ft ($1,075 per sq ft)
Open-market sales since 2016, from the Department of Finance’s sales files.