Across 111 permits filed since 2025-05-04, the median is $117,401; half of projects fall between $53,802 and $200,000. 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 119 sq. ft. one story rear additionVillage of Garden City · 2026-10-30$100,000
- Construct 812 sq. ft. rear roofed over patio additionVillage of Garden City · 2026-10-30$125,000
- CONSTRUCT ONE STORY REAR ADDITION (161 SQ. FT), 25' X 12' REAR PERGOLA, COVERED PATIO WITH OUTDOOR KITCHEN AND FIREPLACE BUILT IN ACCORDANCE WITH NYS AND RVC CODE AS APPROVED BY BZA CASE # 22-22025. DRYWELL, VFR TRUSS PLACARD AND FINAL SURRockville Centre · 2026-10-28$200,000
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 $53,802 and $200,000. 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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