ADU - Accessory Dwelling Units

2020 Updates for ADUs

Ideal Mfg Homes can help you acquire/purchase an ADU as well as help with the installation. We can help you buy a prefab adu, which will save time and money. Contact us today for more information and pricing on Prefab ADU structures.

Accessory Dwelling Units are quickly becoming a topic of interest for San Diego Homeowners. San Diego County allows ADUs and encourages their installation to help off-set the need for additional housing in San Diego County.

General Information on ADU (accessory dwelling unit) and prefab ADUs.

ADUs are often called "Granny Flats", "Tiny Houses" or "Backyard Cottages" due to their smaller size than the main home on the property. They can be legally installed/constructed and will increase the value of the homeowner's property. They can not be sold separately or as a subdivision of the primary property.

Why would you want an Accessory Dwelling Unit on your property? Most people like the idea as a means to generate additional income. They are also very comfortable accommodations for an aging parent(s). And let's not forget that they can help to increase your property value as they will appreciate with the value of your home.

ADUs can be installed or built within residentially zoned neighborhoods. We would suggest that you place a call to your local city planning department to confirm that allowance of accessory dwelling units in your city.

Thinking outside the box

Currently, there is a big push to have residents in San Diego install addition housing (namely ADUs / Prefab ADUs) as were running out of space. Overcrowding and the simple fact San Diego is such a desirable area in which to live. One possibility for residents looking to "down-size" is to move into the ADU yourself and then rent out your primary house. You could create a much larger income from your rental, which in turn could allow you to reinvest, travel, or pursue other things because of your newfound income source.

San Diego County ADU information

PDF linkHere is the current (as of 9/2019) San Diego Planning and Development Services document on ADUs.

In San Diego County, the maximum size of an ADU, if attached to the primary home, is up to 50% of the primary homes square footage. If detached, which are the types we sell, it can be up to 1,200 square feet.

2020 Updates for ADUs

There are a number of new legislative bills that effect ADUs in Califonia

Assembly Bill No. 68

1) Provides zoning ordinance to allow more Accessory Dwelling Units in single-family and multifamily residential zones. The bill removes standards on lot coverage so that you can not put Prefab ADUs on lots proposed or having existing primary dwellings.

2) Reduces the time for authorization to within 120 of receiving the application. This will help you to plan more efficiently rather than waiting long periods, not knowing if you can put an ADU on your property.

3) Removes minimum size restrictions. Additionally, limitations based on lot coverage, floor area ratio, minimum lot size, and open space have been removed.

4) This bill requires ministerial approval of an application for a building permit within a residential or mixed-use zone to create : 

a) one accessory dwelling unit and one junior accessory dwelling unit per lot with a proposed or existing single-family dwelling if certain requirements are met; 

b) a detached, new construction accessory dwelling unit that meets specific needs and would authorize a local agency to impose specified conditions relating to floor area and height on that unit;

c) multiple accessory dwelling units within the portions of an existing multifamily dwelling structure provided those units to meet individual requirements;  

d) not more than two accessory dwelling units that are located on a lot detached from a multifamily dwelling and are subject to a certain height and rear yard and side setback requirements.

5) Reduces need to submit ordinance to the Dept of Housing and Community Development.

6) Removes the requirement to issue a certificate of occupancy to the primary residence before the ADU.

7) Requires cities that do not have ADU specific laws to incorporate the features of this Bill.

8-10) Covers adoption of this Bill with the requirements noted above as well as effecting school districts fees.


Targets obstacles cited by HCD as barriers to creating more of the affordable units. Removes fees on ADUs under 750 square feet. Also removes the requirement that the Accessory Dwelling Unit is owner-occupied.


Pertains to "Separate Conveyances" which allow the Accessory Dwelling Unit to be sold separately from the Primary Residence. We would suggest further research into this Bill to understand the full impact and provisions.


HOA Limitations to prevent HOAs from preventing the installation of an ADU. AB-670 makes it unlawful to restrict ADUs on single-family residential lots.


Requires Local Government Assitance in their General Plan housing provisions to incentivize and promote ADUs.

As you can see, there are many new laws on the books for 2020 that help with the adding of ADUs / Granny Flats to property in residential areas. Please contact us if you have further questions. We can help you with the purchase and installation of a pre-fab ADU, which is generally less costly and better appointed than traditional site-built Accessory Dwelling Units.