Building permits, zoning and septic rules in Westchester County, New York

Yes: New York's Uniform Fire Prevention and Building Code applies throughout Westchester County, and building permits are required for work that must conform to that code, subject to permitted exceptions⁶. Westchester does not provide one building-permit counter for every parcel; the responsible city, town or village ordinarily administers and enforces the code, so identify the municipality before applying^1,6. A local code-enforcement program may exempt listed work such as a one-story detached shed or playhouse of 144 square feet or less associated with a one- or two-family home, certain low partitions, and finish work like painting or tiling, but exempt work must still comply with the Uniform Code¹². The 2025 New York State Uniform Code took effect on December 31, 2025, and local governments cannot exclude themselves from it^6,7. The permit holder must keep covered work accessible until the municipality inspects and accepts it⁶.

Start by identifying which of Westchester's cities, towns or villages your parcel is in, since that municipality's own building or code-enforcement department issues the permit, not Westchester County government¹. As an example of how one of these offices is set up, the City of White Plains Department of Building, at 70 Church St., White Plains, NY 10601, 914-422-1269, enforces the Uniform Code and the city's zoning and building ordinances inside White Plains city limits only¹. Westchester County's own Department of Planning does not issue building permits or set zoning; it can be reached at (914) 995-2000, 148 Martine Avenue, White Plains, NY 10601, but its planning and zoning role is limited to reviewing certain actions that municipalities are required to refer to the County Planning Board². For a definitive answer on permits, fees or inspections for a specific address, contact that address's own municipal building department directly rather than the county².

Zoning in Westchester County is administered at the city, town and village level, so the ordinance for the parcel's municipality is the one a buyer needs to read³. The City of White Plains, for example, publishes its own zoning ordinance and districts, and its figures do not carry over to other municipalities¹³. The Westchester County Planning Board reviews certain planning and zoning actions that municipalities must refer under state and county law, while the county's own page directs questions about specific local development and zoning projects to the individual municipality². We could not confirm a separate countywide zoning ordinance from the reviewed sources. For practical due diligence, ask the parcel's municipal zoning office about permitted uses, minimum lot size, setbacks, accessory dwellings, lot coverage and building height; do not carry an answer from one Westchester municipality into another^2,13.

Environmental engineers in the Westchester County Department of Health review and permit every subdivision plan and every new subsurface sewage treatment system for residential and commercial use to confirm adequate sewage disposal and drinking water^4,5. Plan for that review early: only about 9.7% of Westchester County soils lack severe limits for a conventional septic drain field, making a parcel-specific site evaluation essential before fixing a house location or budget⁹. County engineers also make field visits during construction to verify that the approved plans are followed⁵. Statewide, a septic system discharging less than 1,000 gallons per day of ordinary sewage does not need a state SPDES permit from the DEC, but that exemption does not remove possible county or local health approval before construction¹⁴. If an existing septic system is failing and the property is in the New York City watershed, the county program offers free design and repairs; call (914) 995-7285 to ask about eligibility¹⁵.

We could not confirm one countywide rule allowing residential RV use, temporary camping, tiny homes or manufactured homes on private land in Westchester County. Zoning is administered by the city, town or village where the parcel is located, so ask that municipality's building or zoning office about the proposed use, placement, setbacks and minimum dwelling size before buying or moving anything onto the land^2,13. A tiny home treated as a dwelling must follow the permit process for work subject to the New York State Uniform Code, including construction inspections and a certificate of occupancy or compliance before occupancy⁶. A neighboring municipality's answer is not a reliable answer for your parcel; the Westchester County Planning Department directs questions about specific local development and zoning projects to the individual municipality².

1. Identify the exact city, town or village your parcel sits in; that municipality, not Westchester County, runs building permitting and zoning for it^1,13.
2. Contact that municipality's building or code-enforcement department to confirm zoning, setbacks and what construction documents your permit application needs¹⁶.
3. If the site isn't on public sewer, apply separately to the Westchester County Department of Health's Realty Subdivision and Land Development Review for a septic system permit and plan approval, since this runs through the county regardless of municipality^4,5.
4. Budget for a site evaluation and likely an engineered septic design; only about 9.7% of county soils avoid severe limits for a conventional drain field⁹.
5. Submit your building permit application to the municipal building department, expecting a fee roughly on the order of the state's published schedule, $200 for the first 1,500 square feet plus $100 per additional 1,000 square feet, unless your municipality sets its own fee¹⁰.
6. Complete the required inspections as construction proceeds; the state minimum standards don't require additional periodic inspections of an owner-occupied one- or two-family home once it's built, beyond the inspections tied to the permit itself¹².
7. Obtain a certificate of occupancy from your municipality before occupying the home; only the local authority that issued the permit can grant it, and it requires a final compliance check first¹².

Confirm which of Westchester's municipalities the parcel is in before you assume any building, zoning or fee rule, since County government sets none of those directly^1,13. Get a septic site evaluation from the Westchester County Department of Health early: with only about 9.7% of county soils free of severe limits for a conventional drain field, many Westchester lots need an engineered system, which affects both cost and buildable area⁹. If the property is in the New York City watershed and has an existing septic system, ask the county's Septic System Rehabilitation and Sewer Connection Program whether it qualifies for free repair or replacement design before you assume a failing system is a deal-breaker¹⁵. If you're planning to split the parcel into multiple lots outside an incorporated village, expect town planning board review under New York Town Law, including a public hearing and a decision within about 62 days of a complete application where no environmental impact statement is required¹¹. Budget for Westchester's property taxes at roughly a 1.6% effective rate, translating to a median bill near $10,001 a year on a typical home in the county, well above what many rural counties charge⁹.