Everything homeowners ask about building an ADU in Buffalo — answered with 2026 data.
Yes, ADUs are allowed in Single-family residential zones in Buffalo, NY. The maximum size for a detached ADU is 1,000 sq ft gross floor area; a detached unit must also be shorter and smaller-footprint than the principal building (Green Code UDO 6.1.2.B). Attached ADUs can be up to 800 sq ft. Buffalo has an ADU-friendliness score of 7/10. Check our full Buffalo ADU rules page for complete zoning details.
ADU construction in Buffalo typically costs $110,000-$220,000. The cost per square foot averages $120-$250. Garage conversions are more affordable at $55,000-$130,000, while prefab ADUs cost $80,000-$180,000. Permit fees add $2,000-$3,500 to your budget. See our detailed Buffalo ADU cost guide.
Detached ADUs in Buffalo can be up to 1,000 sq ft gross floor area; a detached unit must also be shorter and smaller-footprint than the principal building (Green Code UDO 6.1.2.B). Attached ADUs are limited to 800 sq ft. Junior ADUs (JADUs) have a cap of Not allowed. Maximum height is 30 feet. You are allowed up to 1 ADU per lot on a qualifying lot.
Rear setback: 15 feet. Side setback: 5 feet. Front setback: 20 feet. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None - Buffalo eliminated all minimum parking requirements citywide in the 2017 Green Code (first major US city to do so). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required by the Green Code - UDO 6.1.2.B contains no owner-occupancy provision. Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Buffalo is typically 50-70 days. Plan check: 2-3 weeks. Pre-approved plans availability: Available for select types.
Average ADU rental income in Buffalo: 1-bedroom units rent for $1,100-$1,500/month, 2-bedroom units for $1,400-$1,900/month. Short-term rentals: Limited. Expected ROI: 8-12% annual return.
The minimum lot size for an ADU in Buffalo is None - the carriage-house building type requires only a 900 sq ft minimum lot area (Green Code 3.2.3). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Buffalo, a garage conversion typically costs $55,000-$130,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.