Accessory Structures
ADU rules, shed permits, and garage conversion regulations.
The 120-square-foot shed is a fixture of American backyards because that is the classic permit-exemption threshold, though plenty of codes draw the line elsewhere. The exemption misleads in both directions. A small shed still has to obey setbacks, and a structure that skipped its required permit surfaces years later, at sale or after a storm claim.
This hub brings together everything on CityRuleLookup related to accessory structures: subtopics, city-specific data, guides, and rankings.
Browse Accessory Structures Topics
ADU Rules
Rules for building accessory dwelling units (granny flats, in-law suites) including size limits, parking requirements, and owner-occupancy rules.
804 locationsADU Impact Fees
Impact fees, school fees, utility hookup charges, and waivers for ADUs. Many jurisdictions exempt ADUs under 750 sq ft from impact fees per state law.
152 locationsADU Owner Occupancy
Whether the property owner must live on-site to operate an ADU, deed-restriction requirements, and recent state-law changes lifting owner-occupancy rules.
281 locationsADU Rental Restrictions
Whether an ADU can be rented short-term (Airbnb), 30-day minimums, separate rental licenses, and long-term lease requirements.
299 locationsShed & Carport Rules
When a storage shed or carport needs a permit, the square-footage exemption thresholds, and the setback and height limits that apply either way.
890 locationsGarage Conversions
Rules for converting a garage into living space, including whether you need to replace the lost parking and what building codes apply.
322 locationsTiny Homes
Zoning rules for tiny houses on wheels and foundations, including minimum square footage requirements and where they can be placed.
251 locationsAccessory Structures by City
Jump to accessory structures rules for a specific city.
Accessory Structures Rankings
Seasonal Accessory Structures Guides
Accessory Structures by State
States with the most accessory structures data on file.
Expert Guides
Most ADU-Friendly Cities in America (2026)
Accessory dwelling units are transforming housing across the country. These cities make it easiest to build one on your property.
Can You Build an ADU? What the Rules Actually Say
Accessory dwelling units are one of the hottest topics in residential development, but the rules governing them are a maze of state mandates and local regulations. Here is what you need to know.
Urban vs Suburban: How Local Rules Actually Differ
City centers and suburbs often operate under the same municipal code, but how those rules play out in practice can be dramatically different. Here is where the gaps show up most.
California ADU Rules: What Homeowners Need to Know (2026)
California leads the nation in ADU-friendly legislation. Here is what homeowners need to know about building an accessory dwelling unit in 2026.
Washington State ADU and Backyard Cottage Rules (2026)
Washington has embraced ADU-friendly legislation. Here is what homeowners need to know about building an accessory dwelling unit in 2026.
ADU and Granny Flat Rules in 2026: What Has Changed
Accessory dwelling unit regulations are evolving fast. Here is what homeowners need to know about building an ADU under the latest rules.