Manufactured Housing Insurance Services®

ADUs / Granny Flat information

New regulations which came into effect on January 1, 2020, help you build Accessory Dwelling Units in California. These bills invalidate local ADU ordinances and replace them with specific state-mandated rules.

Here is a summary of these changes:

Reduced Costs and Burdens for Developing ADUs

  • Cities must approve ADU applications within 60 days, without a hearing or discretionary review.
  • For ADUs permitted by 2025, cities cannot require the owner to live at the property.
  • Cities cannot charge any impact fees for ADUs under 750 sqft; prices for larger ADUs are limited.
  • Homeowners associations must allow the construction of ADUs.
  • ADUs can be constructed at the same time as a primary unit, under most of the same rules.
  • A city must delay code enforcement against an existing unlawful ADU to allow it to be legalized.
  • For areas where development is county-controlled, all of these same rules apply to counties.

ADUs Subject to Automatic Approval — No Local Limits

Cities must permit specific categories of ADU without applying any local development standards (e.g., limits on lot size, unit size, parking, height, setbacks, landscaping, or aesthetics), if proposed on a lot developed with one single-family home. ADUs eligible for this automatic approval include:

  • An ADU converted from existing space in the home or another structure (e.g., a garage), so long as the ADU can be accessed from the exterior and has setbacks sufficient for fire safety. 
  •  A new detached ADU that is no larger than 800 sqft has a maximum height of 16 feet and has rear and side setbacks of 4 feet. 
  • Both of the above (creating two ADUs), if the converted ADU is smaller than 500 sqft.

ADUs Subject to Ministerial Approval — Minimal Local Limits

Even if not subject to automatic approval, a city generally must approve any attached or detached ADU under 1,200 sqft unless the city adopts a new ADU ordinance setting local development standards for ADUs. If a town adopts such a law, it must abide by the following restrictions:

  • No minimum lot size requirements. 
  • No maximum unit size limit under 850 sqft (or 1,000 sqft for a two-bedroom ADU). 
  • No additional required replacement parking is required when a parking garage is turned into an ADU. 
  • No required parking for an ADU created through the conversion of existing space or located within a half-mile walking distance of a bus stop or transit station. 
  • If the city imposes a floor area ratio limitation or similar rule, the limit must be designed to allow the development of at least one 800 sqft attached or detached ADU on every lot.

Adding Units to Multifamily Properties

The legislation now allows units to be added to multifamily buildings. Cities must permit these types of units in multifamily buildings without applying any local development standards:

  • New units within the existing non-living space of a building (e.g., storage rooms, basements, or garages). At least one unit and up to ¼ of the existing unit count may be constructed this way. 
  • 2 new homes on the same lot as the multifamily building but detached from it, with 4-foot side and rear setbacks and a 16-foot maximum height.