Free Feasibility Check
Can I Build an ADU on My Property?
Whether you can build an ADU depends on your state, city, zoning, and lot. Most homeowners in the US can build one — but the rules vary widely. Use our AI advisor to check your specific situation.
Ask Our ADU Advisor
Tell us your state, city, and what you're trying to build. The advisor will look up your local rules and give you a straight answer.
Press Enter to send · Shift+Enter for new line · AI-generated — verify with your local planning department
What Determines ADU Eligibility
Zoning district
Is your lot zoned single-family residential? Most ADU laws apply to R-1/R-2 zones.
Lot size
Some cities require minimum lot sizes of 5,000–6,000 sq ft. Check your local ordinance.
Setbacks
You need enough space from property lines. Most states require 4–5 ft rear and side setbacks.
HOA rules
HOAs can restrict ADUs even where city law allows them. Check your CC&Rs.
Owner-occupancy
Some states/cities require you to live on the property. Many have eliminated this requirement.
Septic capacity
Rural properties on septic may need system expansion to support an ADU.
Historic district
Historic districts often have additional design review requirements that slow or block ADUs.
Utility connections
Separate water/sewer connections add cost and require utility approval.
ADU Rules by State
State law sets the floor — your city may be more or less permissive than what state law requires.
Common Questions
Can I build an ADU on my property?
Whether you can build an ADU depends on your state, city, zoning district, lot size, and existing structures. Most states now require cities to allow ADUs on single-family lots. Key factors: minimum lot size, setback requirements, maximum ADU size, owner-occupancy rules, and HOA restrictions.
What stops most people from building an ADU?
The most common blockers are: HOA rules prohibiting ADUs, insufficient lot size, setback violations (not enough space from property lines), historic district restrictions, and septic system limitations in rural areas.
Do I need to live on the property to build an ADU?
It depends on your state. California, Washington, Oregon, and Colorado have eliminated owner-occupancy requirements. Many other states still require the homeowner to live on the property. Check your state's specific rules.
What is the minimum lot size for an ADU?
Minimum lot size requirements vary by jurisdiction. California has no minimum lot size for ADUs under state law. Many cities require 5,000–6,000 sq ft lots. Your zoning district may also have specific requirements beyond state minimums.
ADU regulations change frequently. Always verify requirements with your local planning department before starting a project. Our AI advisor provides general guidance based on publicly available information — not legal advice.