ADU Zoning in Wilton, Connecticut
What Wilton allows for accessory dwelling units — permitted zones, size limits, parking, rental rules and utilities. Boxx ADUs designs and builds ADUs in Wilton and across Fairfield County. Call us to talk through your property, or send us a message.
Which zones allow ADUs?
All districts. Accessory dwelling units sit under “Uses Permitted in All Districts” (Sec. 29-4.D.1): a single-family dwelling in any district may be converted to include one additional dwelling unit per lot.
It needs a Zoning Permit rather than a Special Permit, so there is no public hearing — an administrative approval.
What types of ADUs are allowed?
Attached or detached. Both units may sit within one building, joined by a common wall, floor or ceiling; the accessory unit may instead be inside an accessory building, or joined to the main house by a breezeway or porch.
Each unit needs its own entrance, which may come off a common hall, and at least one side of each unit must be at or above grade.
What are the size/floor area requirements?
The ADU may not exceed one-quarter of the building’s gross floor area or 750 square feet — whichever is greater. Most neighboring towns apply the lesser of two figures, so on a larger house Wilton is the more generous rule.
No more than two bedrooms.
How many parking spaces?
No parking count is specified for an ADU. But no additional driveway may be created to serve it, so the unit has to work off the existing drive.
What are the rental requirements?
One of the two units must be owner-occupied at all times.
The owner must certify residency by affidavit — both when applying for the Zoning Permit and annually thereafter.
What about utilities, sewer or septic?
The Town Sanitarian must certify that the sewage disposal system is adequate to serve both dwelling units.
What else should I know?
The lot must meet the district’s minimum area and dimensional requirements, and the structure must meet current setback, coverage and bulk rules. One exception: an undersized lot in a two-acre zone created through lot averaging qualifies, provided it is at least 1.8 acres. That exception does not extend to conservation subdivisions or to lots created by variance.
No outdoor stairway serving the accessory unit above the ground floor may be visible from a public street.
Summarized for convenience and current as of publication. Local regulations change — confirm details with the town before relying on them.