Stamford, CT Accessory Structures: ADU Rental Restrictions (2026)

Stamford's Accessory Dwelling Unit (ADU) standards, adopted under application 222-28 effective October 11, 2022, list eleven conditions an ADU must satisfy before the Zoning Enforcement Officer will issue a permit. Condition 10 is unambiguous: ADUs shall not be used as Short-Term Rentals. That prohibition sits inside the same paragraph as the rest of the ADU's operating limits, so a homeowner cannot list an ADU on a booking platform even though ordinary short-term rentals are allowed elsewhere in Stamford's residential zones. The size cap reinforces the restriction: an ADU cannot exceed 800 square feet of gross floor area, occupancy is capped at three persons, and only one ADU is permitted per single-family dwelling.

No more than one single-family dwelling may sit on the ADU lot, and the lot must be at least 10,000 square feet. Legally nonconforming two- and three-family dwellings are excluded from adding an ADU altogether, which keeps the ADU rules confined to true single-family properties. A separate parking condition requires one added off-street space for the ADU, on top of whatever the principal dwelling already needs, with no additional curb cuts. If the ADU is not tied into the public sewer system, the Department of Health and the Environmental Protection Board must first find the septic system adequate for both units before a Zoning Permit issues.

Stamford's separate Short-Term Rental standards, amended under application 223-10 effective June 7, 2023, independently confirm the same ban by defining eligible Short-Term Rental Property to exclude ADUs, so the restriction is written into both provisions of Section 4.