ADU Opportunities in Fairfield and Westchester County: What Homeowners Need To Know

Accessory Dwelling Units (ADUs)—think backyard cottages or in-law apartments—are becoming more popular in Fairfield and Westchester Counties. Thanks to relaxed rules, homeowners now have more options for designing additional living space, supporting affordable housing, creating rental income or accommodating family needs.

Local Rules Matter

Each town and city has its own take on ADUs. Regulations differ on how big an ADU can be, whether it must be attached or can be detached, who can live there, and how properties fit into the surrounding neighborhood. Here’s a quick look at what’s allowed in just some Fairfield County and Westchester County towns and cities.

Fairfield County Highlights:

• Westport: Allows both internal (within main home) and detached ADUs in all zoning districts.  Size limits: Up to 650 sq ft on lots ≤ 1.5 acres; Up to 1,000 sq ft on lots > 1.5 acres

• Fairfield: The ADU must be no larger than 40% of the primary residence’s floor area or 1,500 sq ft, whichever is less.  Also, each ADU must have its own kitchen, bathroom, entrance, and at least one off-street parking space.

• Bridgeport: ADUs in residential zones—great for affordable housing! Size limits and building codes apply.

• Bethel: Strict guidelines about size, occupancy, and where detached units can go.

• Danbury: Mainly attached units are allowed, with limits on size and parking.

• Darien & Fairfield: Support ADUs, but with rules to keep the neighborhood’s character.

• Greenwich: Only attached ADUs, with tight size restrictions.

• New Canaan & Newtown: Very restrictive, focused on family use to maintain community feel.

• Norwalk: More flexible—both attached and some detached ADUs allowed, but owner must live on-site and parking is required.

Westchester County Overview:

• Each town makes its own rules, usually to encourage affordable housing while keeping neighborhoods attractive.

• Owner occupancy is often required.

• Strict design and size standards.

• Permits and architectural review needed.

• Attached ADUs are more common; detached units face restrictions.

• Parking must be off-street to avoid street congestion.

  
  
  
  

Bottom Line:

ADU regulations are all about balancing new housing options with keeping communities livable and attractive. Always check your local zoning department for the latest details—rules change, and each town is different.  One thing is quite clear. New, energy efficient and affordable housing options like ADUs are rapidly gaining popularity as the go-to solution for flexible, multi-purpose living spaces—whether for rentals, home offices, or family needs.