Spring ADU Rules by City & State (2026)

Most Restrictive

1. 1
   Des Plaines, ILShed, gazebo, pergola, detached garage

   Des Plaines has no accessory dwelling unit (ADU) or coach-house ordinance; under Zoning Code Section 12-8-1 a permitted residential accessory structure is limited to a shed, gazebo, pergola, or detached garage and cannot be a separate dwelling, and Illinois has no enacted statute requiring cities to allow ADUs.

2. 2
   Marathon County, WI

   Marathon County zoning flatly bars using a detached garage, shed, or other accessory building as a separate dwelling unit, and residential lots are capped at one house anyway.

3. 3
   Butte County, CA1,200 sq ft (minimum 150 sq ft)

   Butte County permits accessory dwelling units (ADUs) and junior ADUs in unincorporated areas served by municipal water and sewer, with ministerial approval, 4-foot side/rear setbacks, and size caps of 500 sq ft (JADU) or 1,200 sq ft (detached ADU); short-term rentals under 30 days are prohibited.

4. 4
   Coral Gables, FLRequired

   Coral Gables strictly regulates accessory dwelling units through its Zoning Code and Board of Architects review. ADUs are limited to ancillary apartments in select residential zoning districts with significant size, design, and owner-occupancy requirements enforced by Development Services.

5. 5
   Islip, NY300 sq ft minimum; max lesser of 50% or 800 sq ft of principal dwelling GFA

   Islip allows an accessory apartment only within the existing structure of an owner-occupied single-family home, on a lot of at least 7,500 square feet, after a Zoning Board of Appeals public hearing and a permit that must be renewed every three years.

6. 6
   Miami Beach, FL800-1,200 sq ft (varies by district)

   Miami Beach restricts ADUs under its Land Development Regulations. ADUs are permitted only in certain single-family residential zoning districts, must maintain the external appearance of a single-family home, and are subject to strict size and design requirements consistent with Miami-Dade County ADU standards.

7. 7
   Seminole, FLYes, building permit

   Seminole's land development code restricts accessory dwelling units. Most single-family zones allow only one principal dwelling, and second living units require special approval through the Planning and Zoning Division.

8. 8
   Paterson, NJ

   Paterson's zoning ordinance flatly bars any accessory building, garages, sheds, converted outbuildings, from being used for human habitation in residential zones, closing off garage apartments and backyard ADUs.

9. 9
   Cape Coral, FLMaximum size is 800 sq ft or 30% of the primary structure, whichever is less

   Cape Coral does not currently permit traditional accessory dwelling units (ADUs) with full kitchens. Under Land Development Code Section 5.2.11, only detached 'guest houses' are allowed, and only in the Residential Estate (RE) zoning district on lots with an existing principal residence. Guest houses cannot contain a kitchen or even the electrical/gas connections for a stove or oven, may not exceed 800 sq ft or 30% of the primary structure (whichever is less), are limited to one story (14 ft max), and cannot be rented as separate dwellings. Florida has no statewide ADU mandate.

10. 10
    Philadelphia, PARequired; affidavit + deed restriction recorded before occupancy

    Philadelphia permits accessory dwelling units (ADUs) only on lots in the RSA-5 or CMX-1 base zoning districts (and certain overlay districts), under Zoning Code Section 14-604(11). The ADU must be inside the principal building or inside a detached accessory building (such as a detached garage) that already existed as of the Code's effective date, be no larger than 800 square feet, be limited to one per lot, and the owner must occupy either the principal or accessory unit.