- Max size750 sq ft
- Owner occupancyRequired
Wilton, CT permits accessory dwelling units in all districts under Section 29-4.D.1 of the Zoning Regulations. The unit can be inside the principal house, attached by a common wall, in a separate accessory building, or connected by a breezeway. The cap is 750 square feet or 25 percent of the building's gross floor area, whichever is greater, with a maximum of two bedrooms. Wilton opted out of Connecticut's Public Act 21-29, so this local rule governs. The town processes ADU applications administratively as a zoning permit, with no Special Permit hearing required.
Status
- Adoption status
- Active. Section 29-4.D.1 within Uses Permitted in All Districts. Town opted out of Connecticut Public Act 21-29.
- Governing ordinance
- Wilton Zoning Regulations, Section 29-4.D.1 (Accessory Dwelling Units in Single-Family Residences)
- Key differentiator
- ADU cap uses the greater of 25 percent or 750 sq ft, instead of the lesser. Up to two bedrooms permitted. By-right zoning permit, no Special Permit hearing.
Eligibility
Where ADUs are allowed
- Zoning districts permitted
- All districts (Uses Permitted in All Districts)
- Lot type
- Single family lots
- Limit per property
- One ADU per lot
Types allowed
- Attached ADU (within principal building)
- Yes
- Attached ADU (addition with common wall)
- Yes
- Detached ADU
- Yes (separate accessory building)
- Breezeway connection
- Yes (attached via breezeway or porch)
Size and placement
Size limits
- Maximum sq ft
- 750 sq ft, or 25 percent of the building's gross floor area, whichever is greater
- Maximum bedrooms
- 2
- Setback / bulk
- Standard underlying district setback, coverage, and bulk requirements apply
Setbacks
- Setback requirements
- Standard underlying district setback, coverage, and bulk requirements apply to the structure containing the ADU
- Stairway visibility
- Outdoor stairways serving the ADU on any floor other than the ground floor may not be visible from a public street
Rules for use
Parking
- ADU parking requirement
- One off street parking space
- Driveway restriction
- No additional driveways may be created to serve the accessory unit
Owner occupancy
- Required
- Yes. One of the dwelling units must be owner occupied at all times
- Annual certification
- Owner must certify owner residence at the time of initial zoning permit application and on an annual basis
- Separate sale permitted
- Not addressed in 29-4.D.1; the unit is treated as accessory to the principal dwelling
Rental use
- Short-term rental
- Not specifically addressed in 29-4.D.1. Standard Wilton rental rules apply.
- Long-term rental
- Permitted, subject to owner occupancy of either the principal or the ADU
How to apply in Wilton
- Zoning approval
- Zoning permit per Section 29-12D, processed administratively. No Special Permit hearing.
- Annual affidavit
- Owner occupancy affidavit due at initial application and annually thereafter
- Contact
- Wilton Planning and Zoning Commission
Recent and pending changes
- 2020-10-28Amendment 1020-3REG modified Section 29-4.D.1.c (location of accessory units).
- 2010-11-22Amendment 1110-5REG modified Section 29-4.D.1.g (lot size exception for undersized 2-acre-zone lots).
Important details
- Greater-of cap: Wilton's 750 sq ft / 25 percent rule uses the greater value, unlike most CT towns that use the lesser. This produces a more generous cap for larger primary homes.
- Two-bedroom allowance: Wilton permits up to two bedrooms in the ADU. Several CT peer towns cap at one bedroom.
- By-right pathway: ADU applications are reviewed administratively as a zoning permit. No Special Permit, no public hearing.
- PA 21-29 opt-out: Wilton voted to opt out of the Connecticut state default. The local rule applies.
Frequently asked questions
Where in Wilton are ADUs allowed?
ADUs are permitted in all zoning districts under Section 29-4.D.1, which falls within Uses Permitted in All Districts. One ADU per lot, on a single family lot.
What's the maximum size for an ADU in Wilton?
The cap is the greater of 25 percent of the building's gross floor area or 750 square feet, with a maximum of two bedrooms. Underlying district setback, coverage, and bulk rules still apply to the structure.
Do I need a Special Permit?
No. Wilton processes ADU applications as a zoning permit through Section 29-12D. There's no Special Permit hearing required. The owner files an annual affidavit confirming owner residence in one of the two units.
Sources (3)
Last reviewed 2026-04-28. Local rules can change — verify the latest details with the Wilton planning department, or book a free consultation with our team before starting your project. This page is informational and is not legal advice.