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Accessory Dwelling Units

In Collaboration with United Dwelling

ADU Blog
By Derek Leavitt • January 14, 2020

The 12 Most Critical 2020 ADU Rule Changes for California

While California already made huge strides in 2017 with favorable Accessory Dwelling Unit (ADU) legislation, a new series of state bills, signed into law by Governor Newsom at one of our ADU projects, further lower barriers to creating ADUs, aka Granny Flats. Here are the basics of what you need to know regarding the 2020 ADU rule changes for California.

Governor Newson California New 2020 ADU Rules Bills

1. Statewide ADU Law

These 2020 ADU rule changes are statewide in California and all local jurisdictions (cities, counties, etc.) must comply with these new laws starting January 1st, 2020.  If a City doesn't create a new Accessory Dwelling Unit Ordinance, then state law will apply. If a  City creates their own ADU Ordinance, it must comply with these new rules.


2. Now you can add two ADUs to your property!

You are now permitted two ADUs on a single family zoned property, one full Accessory Dwelling Unit (ADU) and one Junior Accessory Dwelling Unit (JADU). A JADU is a 500 sq. ft. max ADU created by converting part of an existing residence (such as a spare bedroom or attached garage).

ADU Junior ADU JADU Los Angeles

3.  Larger ADUs

From 2017-2020, many cities tried to stifle ADU development though local ordinances that severely limited ADU size based on lot size, lot coverage, and a slew of other restrictions. Starting in 2020 you can now build a detached ADU up to 800 sq. ft. and 16' tall without any local discretionary approvals.  ADUs created by conversions are also granted automatic approval.

800 sq. ft. ADU California Los Angeles

If a local municipality creates their own ADU ordinance, it must permit an ADU of up to 850 sq. ft .or 1,000 sq. ft. for an ADU that contains more than one bedroom.  

4. More Parking Exceptions

Parking requirements for ADUs are still one parking space per unit or per bedroom (whichever is less) if you are located more than half a mile from public transit. But starting in 2020, ADUs do not require parking if they are created within an existing space in your house or an accessory structure, like a garage or carport. Additionally, no replacement parking is required for the main residence when a garage or carport is demolished or converted to create an ADU.

ADU Parking Exceptions

5. Reducing Setbacks

Setbacks for new ADUs have been reduced to 4' for side and rear yards. 

6. Remove and Replace a Garage to Retain Setbacks

Big news if you have a garage or carport you want to convert, but determine it is more costly to repair the old structure than it is to replace it. New state law permits you to remove an existing structure and replace it with a new ADU that matches its footprint, maintaining the existing reduced setbacks.  

Remove and Replace Garage ADU or JADU


7. ADUs Can Be Added to Multi-family Dwellings

You can now convert portions of existing multi-family structures that are not used as livable space, such as storage rooms, garages, carports, mechanical rooms, attics or basements to Accessory Dwelling Units . At least one ADU can be created though this method and up to 25% of the existing unit count. For example, if you have an 8-unit apartment building you may be able to add up to two new ADUs by converting existing non-livable space.

If you don't have existing space(s) to convert, but have some leftover land, you can build up to two ground-up, detached ADUs (16’ height limit with 4’ rear and side yard setbacks) on a property with an existing multi-family dwelling. 


Many multi-family dwellings have leftover land for potential ground-up ADUs


8. No Owner Occupancy Requirements Until 2025

One of the new ADU bills (SB-13) signed into law puts a five year moratorium on owner-occupancy requirements that often hinder ADU development. Now you can lease out both your home and ADU! 

9. Impact Fees

Cities will no longer be able to charge impact fees for ADUs under 750 sq. ft. And impact fees for ADUs larger than 750 sq. ft. shall be proportional to the size of the ADU in relation to the primary dwelling.  

Garage Conversion ADU Appliances

Smaller ADUs, like this Garage Conversion ADU by Modative, are not subject to impact fees

10. Shorter Approval Periods

Cities must provide ministerial approval (or denial) of ADUs within 60 days of receiving the application in cases where there is an existing single family dwelling on the lot. The prior rule was 120 days.

11. HOAs

Neither HOAs (Home Owners Associations) nor property CC&Rs (Covenants, Conditions and Restrictions) can reasonably prohibit development of an ADU or JADU.

12. Easier to Legalize Unpermitted ADUs

You now have the ability to bring your unpermitted ADU up to code within 5 years.  


This is just the start.

To learn more, download our free ADU Guide with new 2020 updates.

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