Can I Build an ADU? How to Check in Under 20 Seconds

TL;DR: ADU eligibility depends on zoning, lot size, setbacks, and local rules. ReadyPermit 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.

Lot size minimums — Many jurisdictions require a minimum lot size (typically 4,000–6,000 sqft) before an ADU is permitted.

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.

Lot coverage limits — The total footprint of all structures on your lot (main house + ADU + garage) can't exceed the maximum lot coverage percentage.

Owner-occupancy rules — Some cities still require the property owner to live on-site, though many states have eliminated this requirement.

Utility access — Your lot needs adequate sewer, water, and electrical capacity to support an additional unit.

The 20-Second Alternative

What used to take weeks and $3,500+ in consultant fees now takes 20 seconds. ReadyPermit's ADU Buildability™ Report pulls from 20+ 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. ReadyPermit

	Zoning Consultant	ReadyPermit
Cost	$2,000–$4,500	$29 (first report free)
Timeline	2–6 weeks	20 seconds
Data sources	Manual research	20+ government APIs
Covers	Usually zoning only	Zoning + risk + environmental + market
Reusable	One property	Unlimited addresses

By the numbers: The average zoning consultant charges $2,000–$4,500 and takes 2–6 weeks. ReadyPermit pulls the same data from 20+ government APIs in 20 seconds for $29 (first report free).

Real Example: Sacramento Homeowner

Marcus Webb spent weeks calling Sacramento's planning department about adding an ADU to his backyard. He got conflicting answers from two different planners. When he ran his address through ReadyPermit, the report confirmed his R-2 lot qualified for an 800 SF detached ADU under California state law — with specific setbacks, height limits, and utility connection points. He broke ground the following month.

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 readypermit.ai 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. Backed by FEMA, EPA, USGS, county records, and 16 other government data sources.