5817 21st Avenue, Brooklyn
Two-family · built c. 1925 · Block 5508, Lot 3.
Building permits
- Alteration, filed Nov 5, 2026, estimated cost $175K, described as “Herewith filing an application for the removal of an existing third floor, filing for a rear extension at floors cel-002 and new bulkhead. Filing for an interior renovation at all floors. Filing to address swo & violation 39204224R.”
- Alteration, filed Apr 29, 2026, estimated cost $5K, described as “Temporary construction fence”
- Alteration, filed Apr 29, 2026, estimated cost $10K, described as “Herewith filing for a renovation ofthe front facade with cement andbricks.no change in use, occupancyor egress.”
Property taxes
- Assessment
- $96,960
- 2026–27 tax
- $8,088
- Market value (city estimate)
- $1,616,000
- Taxable value
- $40,759
- Assessed land
- $18,600
- Assessed improvements
- $78,360
Zoning
R5: floor area ratio 1.00 built, 1.50 allowed by base zoning.
Flood zone
Current FEMA flood map: zone X, minimal flood hazard.
Recent sales
- Feb 27, 2017: $998,500
Open-market sales since 2016, from the Department of Finance’s sales files.