Building permits, zoning and septic rules in the Village of Old Westbury, New York

At a glance

Building permit

Required; issued by the village Building Department¹⁴

Zoning

Village zoning code applies inside Old Westbury²

Septic

Local building department for a single home; Nassau County Health Department for subdivisions of 5 or more lots³

Subdivision

Regulated by the village code and, near the boundary, by the county⁵⁶

Certificate of occupancy

Required for work that needed a building permit⁷

Owner-builder

The village lists an owner-as-contractor form¹

Who to call

Contact details are copied from each office’s official page and were checked against it on October 14, 2026.

Does Old Westbury, NY have zoning?

Yes. The Village of Old Westbury adopts its own zoning code, so lot size, setbacks and what you may build on a parcel are set by the village, not by Nassau County². New York counties have no general power to zone, which is why the village code is the one that governs⁸.

We could not confirm the district-by-district numbers (minimum lot size, setbacks, minimum house size, accessory dwellings) or the rules on RVs and tiny homes. Ask the Village of Old Westbury Building Department,¹, which district a specific parcel sits in before you make an offer.

Do you need a building permit in Old Westbury, and who issues it?

The Village of Old Westbury Building Department handles applications for construction, issues building permits and certificates of occupancy, and enforces the village building code¹. New York State requires a building permit for work that must conform to the Uniform Code⁴, and a certificate of occupancy for work that needed a permit⁷.

The state lets a locality exempt small items such as a one-story detached shed of 144 square feet or less⁴. Whether Old Westbury grants that exemption we could not confirm, so call the Building Department before assuming a shed or similar structure is exempt.

Applications, plans, surveys and fees are submitted in person¹.

How do septic permits work inside Old Westbury?

For a home that is not part of a new subdivision, or for renovating an existing home, Nassau County directs applicants to the local building department for septic approval requirements³. In Old Westbury that is the village Building Department, which lists a village application for drywells, private sewage disposal, trench drainage and cesspools¹.

The Nassau County Department of Health has jurisdiction over septic systems in developments of 5 lots or more⁹. Much of Nassau County is on public sewer; ask the Building Department whether a given address is sewered before planning an on-site system.

Can you subdivide land in Old Westbury?

Subdivision is regulated by the village code⁵. The county adds its own layer near boundaries: the Nassau County Planning Commission reviews subdivision applications on properties within 300 feet of a municipal boundary⁶, and the village planning authority must endorse the final map in that case⁶.

A residential subdivision of 5 or more lots also needs Nassau County Department of Health approval of water supply, sewage disposal and drainage plans before construction⁹.

Building a home in Old Westbury: the steps, in order

1. Confirm the parcel's zoning district and any subdivision limits with the village Building Department²¹.
2. Ask the same office about septic or sewer for the address³.
3. Submit the new-home application, plans, survey and fees in person; the Building Department lists forms for new homes, owner-as-contractor, wells and driveways¹.
4. If the project is a subdivision of 5 or more lots, obtain Nassau County Department of Health plan approval⁹.
5. Keep work exposed until inspected, then obtain the certificate of occupancy¹⁰⁷.

What stays with Nassau County, and what to check before you buy

Nassau County does not set zoning; its Planning Commission reviews referred zoning actions and makes recommendations¹¹. The county health department handles septic plan review for larger developments⁹. For rules on land outside village limits, see the Nassau County page.

Nassau County's effective property tax rate is about 1.5%¹², and the median property tax bill is about $10,001 per year¹³. These are county-level figures, not Old Westbury's.

Watch-outs

• Village zoning-district rules, RV and tiny-home rules, and building-permit exemptions were not confirmed; ask the village Building Department¹.
• A road opening or curb cut on a county-owned road involves both the village and the Nassau County Department of Public Works¹⁴.
• Septic approval for a single home runs through the local building department, not automatically the county³.

Sources

1. Village of Old Westbury Building Department (villageofoldwestbury.gov)
2. Village of Old Westbury, NY Code of Ordinances (eCode360) table of contents (Village of Old Westbury), quoted and re-checked
3. On Site Sewage Disposal, quoted and re-checked
4. Part 1203 Uniform Code and the Energy Code: Minimum Standards for Administration and Enforcement (New York statewide rule), quoted and re-checked
5. Village of Old Westbury, NY Code of Ordinances (eCode360) table of contents (Village of Old Westbury), quoted and re-checked
6. Environmental Review, quoted and re-checked
7. Part 1203 Uniform Code and the Energy Code: Minimum Standards for Administration and Enforcement (New York statewide rule), quoted and re-checked
8. documents.dps.ny.gov (New York statewide rule), quoted and re-checked
9. On Site Sewage Disposal | Nassau County, NY, quoted and re-checked
10. Part 1203 Uniform Code and the Energy Code: Minimum Standards for Administration and Enforcement (New York statewide rule), quoted and re-checked
11. Zoning Review, quoted and re-checked
12. Effective property tax rate: Bolthole Index county data
13. Median property tax bill: Bolthole Index county data
14. Building and Zoning Permits, quoted and re-checked

Written October 14, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.