An accessory dwelling unit, a small second home on the same lot, can house a parent, a grown child or a long-term tenant. Westport allows them, and owners have been building them. About 45 permits for detached units had been issued since 2021, the Westport Journal reported in July 2025.
The rules are specific, and they have been revisited in recent years, so treat this as a starting checklist and confirm the current version with the Planning and Zoning office.
The 10-foot separation comes from the Westport Journal’s 2025 report. The other figures come from a February 2024 06880 summary of the rules.
The septic question
North of the Merritt Parkway, where houses generally rely on septic systems, a new unit adds bedrooms, and new bedrooms trigger review by the Aspetuck Health District. The owner must show room on the lot for a full replacement septic system, with at least three test pits about seven feet deep and a percolation test. On a tight lot, that requirement can decide the question before zoning does. Our sewer and septic guide explains how to tell which a house has.
The coverage question
A detached unit counts toward the lot’s building coverage, the share of the lot structures can occupy. On a lot already near its limit, there may be no room left. Have an architect check coverage before you assume a cottage is possible. Our guide to rebuilding explains how coverage is counted.
Renting it out
Because the minimum rental term is six months, an ADU in Westport is a long-term rental or family housing, not a short-term vacation rental. The owner must live on the property.
Sources
- Westport Journal, P&Z, 10 feet must separate house and ADU, July 4, 2025
- 06880, Accessory dwelling units, accessed Oct. 2026
- Aspetuck Health District, B100a information sheet, September 2025
- Town of Westport, Engineering Department, accessed Oct. 2026
