Los Angeles is the latest city to respond to our nation’s housing crisis by rolling out a pre-approved ADU plan program. When a city the size of LA embraces ADUs on this scale, we know we’re making headway!

Now’s the time to learn about pre-approved plans and find out what type of program your city offers.

What are pre-approved accessory dwelling unit plans?

Pre-approved ADU plans are created by city-selected architects or city staff. These plans have already gone through part of the permitting process. They’re less expensive than the typical ADU plan.

With a pre-approved ADU plan, you’ll save the time—on average, around six weeks—that it takes to develop a custom design. You’ll avoid some of the most time-consuming aspects of permitting because there are fewer aspects of the design the city planner has to check. Plus you don’t run the risk of having a minor planning mistake delay the entire project.

Depending on the city, there may be decreased permitting fees because less time is needed for review.

Pre-approved ADU plan cost savings: time and money

The savings in time may be more significant than the savings in dollars. In our experience, buying a pre-approved plan might save you as much as $6000. That’s if you use the plan exactly as-is, without any modifications. If you’re building a $200,000 ADU, $6000 is three percent of your budget.

Three percent is a very small overall percentage of your budget.

Keep it in perspective: For a few thousand dollars, you’re trading the chance to have a completely custom design for a design where you can’t change anything.

Pre-approved ADU plans can make for expensive accessory dwelling units

Just because a pre-approved ADU plan is inexpensive doesn’t mean the unit is going to be inexpensive to build. Accessory dwelling units with large expanses of glass, unusual rooflines, and other special materials or design elements will be costly to construct whether the plan is pre-approved or custom.

Pre-Approved Accessory Dwelling Unit Plans

Pre-Approved Accessory Dwelling Unit Plans

Los Angeles ADU Standard Plan design by SO-IL

Los Angeles ADU Standard Plan design by Amunátegui Valdés Architects

We’re fans of the way Los Angeles has set up its pre-approved ADU plan program, but some of the architects whose ADUs are featured seem out of touch with the average budgets and on-the-ground reality of construction in California.

Multiple angles and large glass walls are beautiful if you can afford them and have the space and views worthy of all those windows. Fortunately, if you do not, some of the LA designs are more practical.

A pre-approved ADU plan is not the same as pre-permitted

There’s a common misconception that you can walk into a planning department, pick a pre-approved plan from their library, and walk out that same day with a building permit. As much as we’d love this to be true, unfortunately, it’s not that easy.

Even with pre-approved ADU plans you still need to hire a designer to:

  • Draw up a site plan
  • Calculate your Title 24s (a report that verifies your building design complies with California Title 24 energy standards)
  • Submit your plans to the city

Many lots also require:

  • Property survey
  • Geo soils report

Another misconception is that pre-approval means you avoid permit fees. Not true. You pay all the same fees as you would with a custom plan.

Change a pre-approved ADU plan? Not so fast

Every scenario, homeowner, and lot is different. There’s no guarantee that a pre-approved plan is going to work perfectly on your property. What if you want to make some adjustments to the design?

If you change something as minor as a window, your plan is no longer pre-approved and you’ll have to go through the whole permitting process just as you would with a custom design.

Curious about the best ADU for your lot and budget? Ask about our free ADU Planning Phone Call.

Two types of pre-approved ADU plan programs

So far, California’s city-sponsored programs fall into two categories:

1.The city owns the pre-approved ADU plans

The city buys ADU plans from selected architects, approves them, and offers them to you either for free or at a price lower than a custom design.

2. Architects or designers own the pre-approved ADU plans

The city does not buy the plans. It verifies that certain plans are approved, and displays the floor plans and/or renderings on the city website. A link connects you to the architect or designer who created the plan. You buy the plan directly from that architect or designer and get the benefit of their support as you go through the permitting and construction process.

Although architecture and design firms charge for their plans, you’ll pay less for one of their pre-approved plans than you would for a custom design.

The downside of city-owned pre-approved ADU plans

All the cities that are rolling out pre-approved ADU initiatives have the right mindset, and we applaud their effort! But there are challenges with city-owned plans you need to be aware of. Over the past couple of years, not many homeowners have chosen to use these plans.

It’s not hard to figure out why. Often there are very few choices in the city-owned selection. More problematic, the city doesn’t offer design support. In theory, you have a set of plans all ready to go, but in reality, it’s not that simple. In addition to the site plans, Title 24 calcs, etc. for which you’ll need to hire outside help, you’re likely to find other hurdles.

Changes to your accessory dwelling unit design must be made by the original architect

What if you live on a hillside or need to change where the front door is located? If you want to make any modifications to your plans, you’ll need to go back to the original architect because there’s a liability issue if an architect who didn’t create the original plans modifies them.

In cities that are offering the plans of only a few architects, this means those architects have a monopoly on the market and can charge whatever they like. You may find someone willing to modify the city plans without having created them, but it’s going to be a person who doesn’t care about liability. Think twice about hiring that person to alter your ADU.

Ask about our free ADU Planning Phone Call to assess your options and educate you on building your ADU.

Cities where pre-approved ADU plans have failed

Santa Cruz was one of the first cities to launch a pre-approved ADU initiative, buying designs from architects and offering them to homeowners.

They only invited seven architects into the program, which cut out a large portion of the architect market. This also greatly limited the types of plans that were available.

The result? A commendable attempt, but no cigar. The limited designs just couldn’t catch the attention of eager homeowners. In fact, they were used less than five times over a period of years.

Encinitas followed suit with its Permit-Ready Accessory Dwelling Units Program (PRADU). This time they had a grand total of two architects. Each architecture firm created four unit types: a studio, a one-bedroom, a two-bedroom, and a three-bedroom, thus creating a library of eight designs. That’s not much variety to choose from.

For both of these cities, the motivation was in the right place. Unfortunately, there were too many limitations, and homeowners didn’t bite. The city programs didn’t result in significant improvements to the ADU market.

Cities with designer-owned pre-approved ADU plans: a better way

Los Angeles’s ADU Standard Plan Program is on the right track, with 28 designs in the hopper and more to come. It posts the firms’ designs on its website along with links to the designers, who in turn sell their plans to homeowners.

Credit: Jopwell Collection


In 2019 San Jose launched its ADU Pre-Approved Master Plan, which is similar to LA’s program. The Master Plan posts links to ADU architects and designers who have created city-approved plans. Homeowners contact the firms to get access to the designs.

This way, homeowners have the counsel and expertise of the original designer while also cutting back on design fees and costs with the city. It’s a much more respectful approach for the designers than just signing away their designs to the city.

It’s a win-win situation.

When you hire an experienced, vetted designer, you’re not just getting the designs to your ADU. You’re also getting:

  • The opportunity to brainstorm with your designer should you want to modify the plan or change to a custom design
  • Professional oversight
  • Hands-free permitting process (your designer should handle all that)
  • Liability-free process (your designer takes on all liability)
Pre-Approved Accessory Dwelling Unit Plans

A San Diego pre-approved ADU plan by DZN Studio

San Jose Mayor Sam Liccardo launched the Pre-Approved Master Plan with high hopes, and they were met: The city went from processing 40 accessory dwelling unit applications in 2016 to 695 in 2019. You can read more about San Jose’s ADU-friendly initiatives here.

The future of pre-approved ADU plan programs

As more cities roll out or expand their initiatives, the designs are likely to get much more practical, cost-conscious, and varied in style. We hope to see more universal design and value engineering. Meanwhile, the city websites are a great place to browse for ideas and inspiration.

If you have the right lot for one of these ADUs and are flexible about what you want (meaning you can live without changing the design), a pre-approved plan might be the right choice for you.

Homeowner education is a vital piece of this process, and that’s where Maxable can help you sift through the promises, possibilities, and misconceptions about pre-approved plans.

From Chico to Chula Vista, cities are actively helping homeowners plan their ADUs—proof that accessory dwelling units are being recognized as a big part of the housing solution. That’s a huge step in the right direction!

Plan, hire, and manage your ADU project with Maxable.

At Maxable, we believe that building an ADU should be fun and exciting. You shouldn’t have to be the one to deal with confusing obstacles like permitting snafus or ever-changing regulations. We’ll be by your side every step of the way and connect you to experienced designers and general contractors in your area to make sure your project goes as smoothly as possible.

Leave the headaches to us! Check your address and see what Maxable can do for your home during a free ADU Planning Call.