Southampton has established clear ADU guidelines that, while having specific requirements, provide a pathway for homeowners to build on their existing property. Whether you're considering a primary residence for a family member, a rental income source, or an independent square footage for your growing family, understanding the local zoning rules is essential to moving forward with confidence. We've reviewed Southampton's zoning regulations in detail and outlined the key requirements below. Rules can change, so confirm details with the Southampton Planning Department or book a free consultation with our team before starting your project.
Where Are ADUs Allowed
ADUs in Southampton are permitted on single-family residential properties. ADUs are permitted on single-family residential properties that meet current zoning district requirements.Each property is limited to one ADU.
Types of ADUs Allowed
Attached (an addition to your existing home that shares a wall, maintaining architectural cohesion with the main structure). Detached (a standalone structure in your backyard, ideal for rental income, multigenerational living, or maximum privacy). Converted (repurposing an existing garage, basement, or accessory structure, often the most expedient option since the shell already exists).
Size Limits
ADU size must comply with Southampton's local zoning requirements. Contact the Southampton Planning Department for specific square footage limits.
Parking
Off-street parking requirements apply to ADUs.
Owner Occupancy
Owner occupancy is required. The property owner must continuously occupy either the main home or the ADU as their primary residence.
Rental Use
Long-term rentals are generally permitted. Short-term rental restrictions may apply, so check local regulations if you're considering Airbnb or VRBO-style leasing.
How to Build an ADU in Southampton
Schedule a free consultation with Haven to confirm your eligibility and walk through your options
Work with a Haven designer to develop your custom ADU project that meets Southampton's local regulations
Haven handles all communication with the municipality and submits your permit application
During construction, the Haven team visits the site regularly to ensure what is being built meets our standards
Certificate of occupancy is issued after the final inspection, allowing the unit to be legally occupied
Permit approval in Southampton typically takes 4 to 8 weeks on average in New York.
Frequently Asked Questions
Q: What's the minimum lot size for adding an ADU in Southampton?
Most of Southampton requires a minimum of 30,000 square feet. However, if your property is in a census-designated place with fewer than 500 people per square mile, the minimum drops to 20,000 square feet. Check with the Town Planning Department to confirm your location's requirements.
Q: Can I rent out my ADU as a short-term rental or Airbnb in Southampton?
No. Southampton's zoning code prohibits having both an accessory apartment and a rental permit on the same property. Additionally, short-term rentals must be 14 days or longer. This means your ADU must be rented long-term to a permanent tenant, not used for vacation or Airbnb-style rentals.
Q: Do I need approval from Southampton's Board of Architectural Review for my ADU?
Yes, if your ADU requires structural alterations to the exterior of the existing dwelling. Before the Building Inspector will issue a permit, the full Board of Architectural Review must approve your plans. This is especially important in the Hamptons area due to aesthetic and historic preservation concerns.
Your property must be a single-family residential lot with appropriate zoning designation to be eligible for an ADU in Southampton. At Haven, we handle the entire ADU process for Southampton homeowners, from zoning verification and design through permitting and construction. Book a free consultation to find out if your property qualifies.