Everything homeowners ask about building an ADU in Jacksonville — answered with 2026 data.
Yes, ADUs are allowed in Select residential districts in Jacksonville, FL. The maximum size for a detached ADU is 25% of primary residence or 750 sq ft (whichever is smaller). Attached ADUs can be up to 25% of primary residence or 750 sq ft (whichever is smaller). Jacksonville has an ADU-friendliness score of 5/10. Check our full Jacksonville ADU rules page for complete zoning details.
ADU construction in Jacksonville typically costs $125,000-$245,000. The cost per square foot averages $155-$305. Garage conversions are more affordable at $60,000-$145,000, while prefab ADUs cost $90,000-$210,000. Permit fees add $3,200-$5,000 to your budget. See our detailed Jacksonville ADU cost guide.
Detached ADUs in Jacksonville can be up to 25% of primary residence or 750 sq ft (whichever is smaller). Attached ADUs are limited to 25% of primary residence or 750 sq ft (whichever is smaller). Junior ADUs (JADUs) have a cap of Not allowed. Maximum height is Must not exceed height of primary residence. You are allowed up to 1 ADU per lot on a qualifying lot.
Rear setback: 20 feet. Side setback: 5 feet. Front setback: 25 feet. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
1 space. 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. 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 Jacksonville is typically 80-110 days. The plan check process takes approximately 3-4 weeks. Pre-approved plans availability: Not available.
Average ADU rental income in Jacksonville: 1-bedroom units rent for $1,100-$1,600/mo/month, 2-bedroom units for $1,400-$2,000/mo/month. Short-term rentals: Varies by district. Expected ROI: 6-8% annual return.
The minimum lot size for an ADU in Jacksonville is 7,500 sq ft. 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 Jacksonville, a garage conversion typically costs $60,000-$145,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.