Across 496 permits filed since 2025-05-02, the median is $52,700; half of projects fall between $15,000 and $600,000. 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 Fairfield County, CT actually reported when they pulled permits.
Recent filings
- FINISH UNFINISHED PORTION OF BASEMENT FOR OFFICE AND PLAYROOMWestport · 2026-10-29$32,000
- Rough and finish work for basement bathroom with pump for toilet, shower stall, lav sink and bar sinkTown of Weston · 2026-10-28$6,000
- TWO-STORY SINGLE-FAMILY DWELLING WITH FINISHED BASEMENT AND FINISHED ATTIC, 6 BEDROOMS.Westport · 2026-10-28$915,000
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 Fairfield County, CT came in between $15,000 and $600,000. 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