Across 69 permits filed since 2025-01-25, the median is $120,000; half of projects fall between $45,001 and $180,000. 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 Nassau County, NY actually reported when they pulled permits.
Recent filings
- Construct a 170 sq. ft. first floor addition with a 75 sq. ft. portico at the front, and a 2,060 sq. ft. full second floor addition (demolish 168 sq. ft. rear porch and 1,385 sq. ft. 2nd floor),Village of Garden City · 2026-07-22$392,000
- Residential Piping & Fixtures - Run piping for new additionsVillage of Garden City · 2026-07-22$15,000
- Construct 161 sq. ft. first floor expansion of an existing rear screen Porch, with a 373 sq. ft. second floor addition aboveVillage of Garden City · 2026-07-22$280,000
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 home addition permits in Nassau County, NY came in between $45,001 and $180,000. 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
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