Across 501 permits filed since 2025-04-24, the median is $14,000; half of projects fall between $4,500 and $50,000. Figures are permit valuations reported to building departments. National cost guides answer this question with averages from other markets; these numbers are what homeowners in Westchester County, NY actually reported when they pulled permits.
Recent filings
- Legalization of existing shower, sink and toilet for a basement bathroom.Village of Ossining · 2026-10-23$1,000
- New Construction 3 bedroom dwelling 3.5 Bathroom, finished basement, covered deckTown of North Castle · 2026-10-23$628,000
- New Construction 3 bedroom dwelling 3.5 Bathroom, finished basement with full bathroomTown of North Castle · 2026-10-23$628,000
How to read these numbers
Permit valuations are the project cost the applicant reports to the building department. They skew slightly low — nobody rounds up for the permit fee — and scope varies, so the middle-half range is the honest picture: half of all basement finishing permits in Westchester County, NY came in between $4,500 and $50,000. We exclude permits under $1,000, jobs filed as whole-house construction, and counties whose building departments don't reliably report valuations.
Same project, other places
Basement finishing in New YorkBasement finishing in ConnecticutBasement finishing on Long Island