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The cost to build an ADU in Southern California varies by location, available space, personal preferences and more.

What is the Cost to build an
Accessory Dwelling Unit?

Granny Flats
Backyard Offices
Garage Conversions

Understanding the cost to build an ADU
in Southern California

Build a Single Family Home |$637,000+

Build a Backyard ADU |$168,750+

If you are thinking about building an ADU, you have no doubt learned that the median home prices in Southern California are astronomical! Highest as of 2021 Orange County: $1,120,000. Lowest: San Bernardino County: $445,000 Many Residents are looking at their options when their family dynamics change and they need new solutions for comfortable living arrangements. When you consider how costly it is to build a new single family home these days, the idea of building an ADU becomes much more appealing when you can do it for a fraction of the cost!

Baseline costs to build an ADU or Granny Flat


The following numbers are approximations. Once we have an understanding of your location, design, fixtures and other factors, we can then be more definitive. There are multiple factors that dictate the cost of your build. This can include, but not limited to the unstable building materials industry and the city of your build. SoCal-ADUPros will 100% do what’s necessary to ensure you receive the best pricing without compromising craftsmanship or value. As long as there are no extenuating circumstance, Client can expect approximately, $240-$260 per SF. *Costs are subject to fluctuate due to the volatile materials and supplies market. The day of contract signing secures pricing.



1 Bedroom ADU 500 Sq Ft – $120,000 – $130,000

2 Bedroom ADU 750 Sq Ft – $180,000 – $195,000



2 Car Garage Approx. 400 Sq Ft - $84,000 - $92,000

3 Car Garage Approx 600 Sq Ft - $126,000 - $138,000

* We suggest to all clients that they let us know their budget. Once we have an understanding of your budget, we can then give you the best value for your budget.

* The cost to build ADUs vary largely, depending upon personal preferences, allowable space, utilities and permits.

* Save yourself some time and money, have one of our expert Team Members evaluate your needs and give you an accurate assessment.


Multiple inspections are required until the project is finished. If one of your inspections fails, you have to apply for a new permit and pay the fees again.

[SoCal-ADUPros won’t let this happen.]

*Southern California permits all have expiration dates. If your project falls off of the timeline for any reason, you will be required to apply for another permit and pay the fees again.[SoCal-ADUPros won’t let this happen.]

*Hiring multiple contractors like an architect, a designer and construction crew to build your project is the fastest way to blow your ADU construction costs off the chart. This method creates delays, mistakes, miscommunication, failed inspections and unnecessary costs.

*SoCal-ADUPros is a One-Stop, Full Service experience. We are a complete team. Designers, Architects and Construction crews all under one roof. We take care of EVERYTHING including obtaining permits and coordinating inspections. Our Crew has been working together for over years and we are a finely tuned machine. We greatly reduce your exposure to the list of UNexpected, UNnecessary costs.


Licenses and Building Codes

Utility Fees and Taxes

Plan Reviews

Permit Fees

School Fees

Impact Fees (If you build over 750 sq ft.)


*when you choose the wrong builder

City-Required property upgrades

Failed Inspections

Expired Permits / New Applications

Expedited Permits

After-Hour Inspections

[You can expect SoCal-ADUPros to avoid unexpected costs.]

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Can you build an ADU? Find out.

Connect with the SoCal-ADUPros Team today.
We're ready to help.

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