Bristol allows one ADU per home lot, attached or detached, between 360 and 900 sq ft, if the owner lives on site. The zoning board decides each one.
The code allows an ADU only with a special use permit, which a board must approve, usually after a public hearing. Approval is not automatic.
Whether any of this applies to your lot depends on your zoning district and your property.
The rules we found
| What the code says | Allowed with a special use permit |
|---|---|
| Detached (backyard) unit | Yes. The definition covers a unit detached from or inside a single-family home |
| Inside or attached | Yes |
| Size limit | At least 360 sq ft; no more than 900 sq ft or 40% of the main home's gross floor area, whichever is smaller |
| Bedrooms | None stated |
| Owner must live on site | Yes. The owner's primary home is one of the two units, and the owner owns both |
| How approval works | Zoning Board of Appeals special use permit |
| Other rules | Allowed in all residential districts, one per lot. Not allowed on a lot with a two-family home or apartment building, or with an open code violation unless the ADU fixes it. It must sit on a permanent foundation, and you can't add a new driveway just for the ADU. |
Code section: §350-54.1 Accessory dwelling units. February 12, 2024 (Local Law 1 of 2024)
What the size rule means for your house
With a 1,600 sq ft house, the largest ADU this rule allows is about 640 sq ft.
The smallest ADU allowed here is 360 sq ft, so the house needs about 900 sq ft or more for any ADU.
sq ft
Rounded down to the nearest 10 sq ft. Towns measure differently (some count only finished living space, some leave out the garage), so ask the code office how it measures yours.
What this means for your plans
- Expect a public hearing where neighbors can speak, and a board decision that can take a few months. How special use permits work.
- The owner has to live on the property. If you plan to move away, spend winters somewhere else or sell, read the owner rule above closely. Renting and owner rules.
What we’re still confirming
- Town Board minutes from Aug-Oct 2025 mention ADUs; whether an amendment followed was not checked
Before you spend money on drawings
- Confirm the Town of Bristol governs your lot: it should be the municipality on your property tax bill.
- Find your zoning district on the municipal zoning map; the rules above can differ by district.
- Call or write the code office with your address and what you’re picturing, and ask for the answer and the code section in writing.
- On septic or a well? Ask the NYS Department of Health’s Geneva District Office (315-789-3030) whether the system can serve an extra bedroom. On public sewer? Ask your sewer district.
Our guides explain the approval process, site and utility checks and what an ADU costs.
Sources
General information, not legal advice. The Town of Bristol decides what can be built on your property.