Blog · ADU
Can I Build an ADU? How to Check in Under 20 Seconds
Landon Reid · Founder, Buildability™2026-03-20 · 5 min
TL;DR: ADU eligibility depends on zoning, lot size, setbacks, and local rules. Buildability™ checks all of these instantly for any U.S. address — free, no signup required. What used to take a $3,500 consultant now takes 20 seconds.
The ADU Question Everyone's Asking
Accessory dwelling units are the hottest trend in residential real estate. With new state laws in California, Oregon, Washington, and dozens of other states making ADUs easier to build, homeowners and investors are scrambling to find out: can I build one on my property?
The old way to answer that question involved calling your local planning department, waiting on hold, getting transferred, and — if you were lucky — getting a vague answer a few days later. If you wanted certainty, you'd hire a land use consultant for $2,000–$5,000 and wait 3–6 weeks.
What Determines ADU Eligibility?
ADU eligibility depends on a surprisingly complex set of factors:
Zoning Classification
Not all residential zones allow ADUs. Some require a conditional use permit. Others allow them by right under state preemption laws. This is the first thing to check — and the most common reason ADU plans fall apart.
Lot Size Minimums
Many jurisdictions require a minimum lot size (typically 4,000–6,000 sqft) before an ADU is permitted. Some states have overridden local minimums, but your city may still enforce them.
Setback Requirements
Your ADU needs to meet rear and side setback requirements, which vary by jurisdiction. Some states have reduced setbacks to as little as 4 feet under recent legislation — a game-changer for smaller lots.
Lot Coverage Limits
The total footprint of all structures on your lot (main house + ADU + garage) can't exceed the maximum lot coverage percentage. This is where many projects get stuck.
Owner-Occupancy Rules
Some cities still require the property owner to live on-site, though many states have eliminated this requirement. Check your local ordinance — this varies widely.
Utility Access
Your lot needs adequate sewer, water, and electrical capacity to support an additional unit. Connection fees can add $5,000–$20,000 to your project.
The 20-Second Alternative
What used to take weeks and $3,500+ in consultant fees now takes 20 seconds. Buildability™'s ADU Buildability™ Report pulls from official government data sources to instantly determine:
- Whether your zoning district allows ADUs (by right or with permits)
- Your lot's setback requirements and remaining buildable area
- Maximum ADU size allowed under local and state regulations
- Estimated rental income potential based on local market data
- Environmental constraints (flood zones, fire hazard areas) that could affect construction
Instead of spending weeks on research, you get a comprehensive answer in 20 seconds.
What It Costs: Consultant vs. Buildability™
| Zoning Consultant | Buildability™ | |
|---|---|---|
| Cost | $3,500+ | 1 credit per report (3 free to start) |
| Timeline | 2–6 weeks | 20 seconds |
| Data sources | Manual research | Live government APIs |
| Covers | Usually zoning only | Zoning + risk + environmental + market |
| Reusable | One property | Unlimited addresses |
The average zoning consultant charges $3,500+ and takes 2–6 weeks. Buildability™ pulls the same data from live government APIs in 20 seconds — one credit for the full Buildability™ Report with Geo™ AI. First report is free.
When to Start Your ADU Research
The best time to check ADU feasibility is before you need the answer:
- Before buying a property — Check ADU potential as part of your due diligence
- Before hiring an architect — Know your constraints before paying for plans
- Before talking to contractors — Have your zoning data ready to share
- Before refinancing — ADU potential can significantly impact property value
Check Your Property in 20 Seconds
Enter any U.S. address at buildability.us and get your ADU Buildability™ Report instantly. Your first report is free — no signup, no credit card.
What consultants charge $3,500+ for is yours in 20 seconds.