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How to Choose the Best ADU Builders in San Diego

Learn how to evaluate and choose the right ADU builder in San Diego for your ADU project.

January 5, 2024

San Diego has become one of the hottest cities in the U.S. for ADUs. According to our 2023 ADU Impact Report, San Diego makes up 10% of all ADU permit applications in California. This is great news for the housing market – in the face of San Diego’s housing crisis, ADUs offer an affordable housing solution. What’s more, they add valuable living space for San Diego homeowners to use for everything from housing family and renting out to using the ADU as flexible space.Since changes to California’s ADU regulations went into effect in 2020, more and more homeowners have pursued an ADU for their property. Remember, ADUs are permanent homes that are built to last for generations, so finding a reputable contractor to take on your project is critical. Let’s dive into what you should consider when selecting the right ADU builder in San Diego.

Why Hire an ADU Builder?

There are a lot of general contractors out there, each with their own set of expertise. When it comes to choosing a builder for your ADU, it’s important to work with one who has extensive experience building ADUs. Here’s why: ADUs have their own set of regulations in San Diego. As long-term housing, these living spaces are heavily regulated and must meet certain building and safety codes. Working with a contractor that specializes in ADUs and has knowledge of these regulations will ensure a successful project.

Here’s why it’s a good idea to work with a contractor that has ADU experience:

  • Expertise: An experienced builder brings specialized knowledge of local regulations, ensuring your project not only complies with standards but also swiftly passes inspections – thus expediting the move-in process.
  • Commitment to Quality: Seasoned builders prioritize quality in ADU-specific elements of construction, such as electrical and plumbing, solar, and more. Their expertise goes beyond meeting basic requirements, focusing on emphasizing safety, aesthetics, and long-term durability for your project.
  • Cost-Effective Solutions: Established builders can access bulk discounts from material providers, a perk of working on multiple ADU projects concurrently. This cost efficiency translates to savings for you without compromising on quality.
  • Efficient Timelines: With their experience and skilled teams, ADU builders are capable of constructing an ADU much faster than contractors who specialize in other types of construction.
  • Project Management: experienced builders have experience juggling all aspects of an ADU project, from ordering materials to the construction itself, to navigating inspections.

Criteria for Choosing ADU Builders in San Diego

With all the contractors in the marketplace, it can be near impossible to know what to look for when choosing your builder. No two contractors are the same, making it challenging to discern the key qualities that set them apart.

After working on ADU projects across the greater San Diego area, here are the qualities we’ve found to be non-negotiable when it comes to selecting your contractor.

1. Experience building ADUs in San Diego

Having experience completing multiple successful ADU projects is a must-have when you’re choosing a contractor. Despite their relatively small footprint, ADUs often involve unique challenges and intricacies that differ from full-sized homes, kitchen remodels, and other construction projects. Select a builder that understands the ins and outs of these intricacies and can successfully navigate the ADU construction process.

Take this San Diego homeowner, for example. They worked with a vetted contractor from our Builder Network and were thrilled with the quality and customer service we delivered. The contractor was able to shed light on numerous unknowns throughout the process – from the feasibility of the patio’s accordion-style doors to the pricing of selected finishes, and more. Schedule a call with our team today to learn more about our San Diego contractors.

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2. Understanding of ADU requirements in San Diego

Despite California having statewide ADU regulations, no two cities have identical ADU regulations. To ensure the success of your project, it’s critical that your contractor understands the local requirements in detail.

Throughout construction, your builder will need to correspond with city inspectors and other entities like San Diego Gas & Electric (SDGE). Familiarity with San Diego’s ADU requirements is instrumental in navigating the necessary inspections seamlessly. Look for an ADU builder in San Diego that’s poised to navigate all aspects of local ADU regulations during the construction process.

3. Positive reviews

A good general contractor will not hesitate to provide references to some of their past clients. These homeowners will have the best insight into what it’s like working with this builder.

Some helpful questions you can ask past clients include:

  • How was the contractor’s communication and transparency?
  • How often were they or the site manager on site? (Keep in mind that general contractors have a lot of work behind the scenes, so they may not be present on your site every working day. However, your project manager should always be available to support you should anything arise.)
  • What kind of obstacles arose and how did your general contractor resolve them?
  • Did they stick to the timeline and budget?
  • Overall, were you happy with your experience working with this general contractor?

At Cottage, we recognize the challenge of finding a reliable contractor that checks all the boxes. Our vetting process includes speaking with prior clients to hear their experience first-hand, as well as reviewing the builder’s completed projects and assessing sample bids.

We’ve vetted countless contractors in San Diego and selected the best to join our ADU Builder Network. With Cottage, you’ll get multiple competitive bids – which not only means you’re getting the best value, but means you don’t need to research ADU contractors yourself (saving you time and energy!). Hear what our homeowners say on Houzz and Google about working with Cottage.

4. Licensed & fully insured

California requires that all general contractors accepting jobs valued over $500 need to be fully licensed and insured to protect the homeowner. At Cottage, we make sure that all the contractors we work with hold the required licenses and insurance.

While your builder should be the expert of all things to do with construction, it’s a good idea to familiarize yourself with some of the regulations for ADUs in San Diego so that you can actively participate in the decision-making process and ensure compliance with local guidelines.

An Overview of ADU Regulations in San Diego

San Diego is one of the most progressive cities in California when it comes to ADUs. The city has passed numerous ordinances that go above and beyond state regulations to make building an ADU even easier.

While this is great news, all these new regulation changes can lead to some confusion about what is actually required for your ADU. In short, an ADU needs to provide complete independent living facilities. This means it must include permanent provisions for living, sleeping, eating, cooking, and sanitation, as well as have an exterior entrance that’s separate from the primary dwelling.

Below is a quick overview of ADU regulations in San Diego. Interested in the specifics? We’ve compiled all the details of ADU requirements in San Diego County and the City of San Diego.


All properties zoned for single-family and multi-family use in San Diego are eligible to build ADUs.

Number of Units

Did you know that single-family properties in San Diego can add up to three additional living spaces on their property? Thanks to new regulations, you are permitted to build one attached ADU, one detached ADU, and one junior ADU (JADU) on a property zoned for single-family use.

Building Size

The maximum size for ADUs in San Diego is 1200 sq. ft. for detached ADUs, a full 400 sq. ft. larger than the state regulated max size of 800 sq. ft. The minimum size for an ADU in San Diego is 150 sq. ft.

As for height, the maximum height for detached ADUs is 16 ft., and sometimes up to 24-30 ft. depending on the zone your property is in.


In San Diego, ADUs below 16 ft. in height are allowed to have 0 ft. side and rear setbacks. That means you can push your ADU all the way to the property line!

ADUs that exceed 16 ft. are subject to 4 ft. side and rear setbacks, and 6 ft. setbacks from existing structures. This includes two-story ADUs and ADUs built above a garage. However, if you are converting an existing space into an ADU or demolishing an existing space to make room for an ADU, you may observe the setback regulations of the original structure.

Parking Requirements

Thanks to new regulations, off-street parking is not required if your ADU meets at least one of the following: The ADU is located within one-half mile walking distance of public transit The ADU is located within an architecturally and historically significant historic district The ADU is part of the proposed or existing primary residence or an accessory structure When on-street parking permits are required but not offered to the occupant of the ADU When there is a car share vehicle located within one block of the ADU

Depending on your neighborhood, public transit locations like bus stops and train stations are plentiful in San Diego, so odds are you won’t have to include off-street parking just with that first bullet point alone.


San Diego’s initiative to make ADUs easier to build is a response to a severe housing shortage. City officials that have passed ADU ordinances recognize that ADUs are excellent options for long-term housing, which is why ADUs are not allowed to be rented for less than 30 days, making vacation rentals on Airbnb or VRBO a no-go.

The good news is that ADUs are highly sought after by long-term renters in San Diego as they offer more privacy and are better designed than apartment complexes. With San Diego hosting large medical facilities and universities, ADUs are also popular among traveling nurses and professors looking for mid-term leases of four to six months.

It’s important to note that although ADUs do not require owner occupancy, junior ADUs (JADUs) do require owner occupancy, making these a less desirable option for investors.


All homeowners wanting to build an ADU in San Diego are required to obtain a building permit. Other permits may be required based on project scope, lot characteristics, and property location. The builder you choose should know how to navigate these regulations seamlessly.


On average, an ADU can cost around $200,000-$400,000 depending on your ADU type, location, size, and other specifications. To get a sense of what you’ll be spending, it’s helpful to break up ADU costs into soft and hard costs.

Soft costs include fees around designing your ADU, working with consultants, and securing permits. Although construction makes up the majority of your overall ADU cost, these fees are critical to getting your ADU project off the ground.

Hard costs include site preparation, materials, labor, utilities, and finishes. This is where the costs will largely vary depending on your ADU size, site conditions, design, and level of finishes.

The hard costs of your ADU will depend on the ADU contractor you choose. If you work with Cottage, you’ll know you’re getting the best price out there: we provide you multiple line-item bids from vetted contractors in our Builder Network.

Design and Build Your San Diego ADU With Cottage

Cottage exists to help you get a custom ADU designed just for you – at the best value, and through our streamlined process. From feasibility, to design, permitting, and construction, we can support you through every stage of the ADU journey. Here’s how it works:

1. Feasibility: We’ll discuss your goals and work with you to scope your project based on your property, design vision, and budget.2. Design & Bid: Work 1:1 with your dedicated Designer on architecture and interiors, then get competitive bids from vetted contractors in our Builder Network.

3. Permitting: Sit back while your designs are developed into plan sets. We handle the entire permitting from submission to approval.

4. Construction: We support you and your contractor to get your project across the finish line - on time, and on budget.

Ready to get started? Book a free consultation call and see what’s possible on your San Diego property!


How much does it cost to build an ADU in San Diego?

On average, an ADU can cost around $200,000-$400,000 depending on your ADU type, location, size, design, and other specifications. Our team of ADU experts at Cottage provides a full feasibility analysis of your property. Using this research and your design vision, we’ll provide you with tailored budget guidance for your project.

What is the cheapest way to build an ADU in California?

Garage conversions are the most cost-effective way to build an ADU since you’re working with an existing structure. However, the feasibility of a garage conversion project depends on the condition of your garage. Our team can help you understand if a garage conversion is possible on your property.

What is the minimum ADU size in San Diego?

The minimum ADU size in San Diego is 150 sq. ft. The maximum ADU size is 1200 sq. ft. or larger if you are converting an existing structure, such as a garage, that is larger than 1,200 sq. ft.

Is it worth building an ADU in San Diego?

Yes! There are many long-lasting benefits to building an ADU in San Diego. ADUs add valuable living space to your property. Whether you use this space to house family, work from home, rent out, or something else, ADUs help you make the most out of your property.

Additionally, an ADU can increase your property value by up to 30%. When it comes time to sell your property, ADUs are a big selling point for potential buyers as they can be used as rentals for passive rental income.

Who are the best builders in San Diego?

The best ADU builders in San Diego may vary according to your needs, but they should have experience building ADUs, top-notch customer service, and a solid grasp of the ADU regulations in San Diego. If you’re a homeowner in San Diego looking for a reputable ADU builder, good news: Cottage has already done the legwork for you. Our team has vetted hundreds of local builders in San Diego and accepted only the best to our Builder Network.