Can I Build an ADU on My Property?
Data version: Q2 2026 · Last updated 2026-05-13
TL;DR. Find out if your lot qualifies for an accessory dwelling unit. Buildability™ checks your zoning, lot size, state law, setbacks, parking, and owner occupancy requirements in about 20 seconds. The first check is free and no signup is required. Coverage spans all 50 states with deep data for California, Oregon, Washington, Colorado, Texas, Florida, and New York.
What is an ADU?
An ADU (Accessory Dwelling Unit) is a secondary housing unit on a single-family lot. Common types: detached ADU (new construction in backyard), attached ADU (addition to main house), JADU (Junior ADU — a bedroom converted within the main house with a kitchenette), and garage conversion. ADUs are the fastest legal path to adding rentable or family housing on an existing single-family lot.
ADU rules vary by state
California: state law (AB 68, SB 9) forces cities to allow at least one ADU on most single-family lots, with streamlined 60-day permit review. Oregon: HB 2001 requires cities over 2,500 population to allow duplexes and middle housing on single-family lots. Washington: HB 1110 requires medium and larger cities to allow 2-4 units per lot. Texas and Florida: no statewide ADU law, so rules vary city-by-city. Buildability™ checks both state law and local ordinances.
Typical ADU constraints
Maximum size is usually 800-1,200 sqft. Maximum height is usually 16-25 feet. Side setbacks are typically 4 feet minimum. Parking is often waived for ADUs within 0.5 miles of transit. Owner occupancy was required in many cities but has been eliminated in most California jurisdictions. Lot coverage and FAR may limit the combined total of house + ADU.
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