5912 21st Avenue, Brooklyn
Two-family · built 2005 · Block 5514, Lot 41.
Building permits
- Alteration, filed Dec 24, 2025, estimated cost $2K, described as “Filing for proposed concrete parking pad and exterior wall adjustment. Work as per plan. Filing for plan layout details in conjunction to Alteration CO adding a fourth floor to the existing 3 story building. Filing to comply with violation…”
- Alteration, filed Dec 24, 2025, estimated cost $2K, described as “Filing for curbcut application.”
- Alteration, filed Nov 6, 2025, estimated cost $1K, described as “Proposed installation of temporary pipe scaffold as per plans. Work shall comply with chapter #33 of 2022 the NYC building code. No change in use, occupancy, or egress under this application.”
Property taxes
- Assessment
- $205,200
- 2026–27 tax
- $23,008
- Market value (city estimate)
- $3,420,000
- Taxable value
- $115,949
- Assessed land
- $35,340
- Assessed improvements
- $169,860
Zoning
R5: floor area ratio 1.73 built, above the 1.50 base zoning allows, which bonuses, transfers or older rules can permit.
Flood zone
Current FEMA flood map: zone X, minimal flood hazard.