What Qualifies as an ADU?

Choosing the Right ADU for Your Property

Selecting the right ADU style is an important decision that depends on your property size, budget, and goals. Whether you’re aiming to create a private rental unit, a multigenerational living space, or a cost-effective way to add square footage, each type of ADU has unique benefits and challenges. The table below provides a quick comparison of ADU styles to help you determine which option best fits your needs. The next section will dive deeper into each style to guide you through the pros and cons in detail.

Types of ADUs

While pool houses would not be considered accessory dwelling units because they often do not contain a functional kitchen, many other types of structures do qualify as ADUs. There are several types of ADUs, and which type you choose to build on your property often comes down to budget, property size, and intended use.

Detached ADU

A detached ADU, or an accessory apartment, is what most homeowners think about when they think of an ADU.

Detached ADUs are also sometimes referred to as backyard cottages, guest houses, or granny flats and are a popular choice for homeowners looking to maximize rental income while maintaining privacy. Building a detached ADU is a more expensive option due to new construction and new utility connections, and it does require a fairly sizable yard to accommodate both the size of the accessory structure and the setback requirements.

Plan for utility connections and setback distances when designing detached ADUs to maximize privacy and functionality.

Attached ADU

Attached ADUs are added onto existing residences and share a wall with the primary dwelling unit, though it may not be accessible to the primary dwelling from the inside.

They are popular among budget-conscious homeowners with limited yard space or those who are looking to modify their home for long-term, multi-generational living.

Attached ADUs are often confused with JADUs or Junior Accessory Dwelling Units, but they’re different: An attached ADU involves new construction, while a junior accessory dwelling unit is created within a home’s existing walls. JADUs may have different permit requirements and code requirements from traditional ADUs. Make sure you’re working with a builder who knows the differences and zoning codes for both.

Ensure seamless integration by addressing utility connections and structural reinforcements for attached ADUs.

Garage Conversion

If you have a garage that’s not getting much use, you may consider converting it into an additional dwelling unit, as many of our clients have. Garage conversion ADUs can offer all the benefits of a traditional detached ADU in terms of privacy and potential rental income, but they can generally be built more quickly and cost-effectively, as the main structure is already built.

Before beginning a garage apartment, you will want to think about how parking and storage may be impacted and make a plan. You will also want to work with a builder experienced in ADU construction who can help you upgrade the insulation and utilities as necessary.

Upgrade insulation and utilities for garage conversions, and plan parking solutions to offset lost garage space.

Basement Conversion

Similarly to garage conversions, if you have an unfinished basement that can accommodate a separate exterior entrance, you may consider converting it to an ADU for extra living space. Remember, a separate entrance is key to building a proper ADU. If a basement apartment is only accessible via the main home, it is not an ADU – though it can be used as an in-law unit.

Along with potentially adding a new entrance, homeowners looking into a basement conversion also need to consider adding extra ventilation and waterproofing to keep the unit dry and comfortable.

Prioritize waterproofing, proper drainage, and adding a separate entrance to convert basements into ADUs.

Above-Garage ADU

If you don’t want to sacrifice your entire garage for an ADU conversion, you can consider adding a loft or apartment above your garage as a rental property or a separate home office.

Above-garage ADUs add extra living space to your property without taking away yard space, but they can be associated with higher costs than a traditional garage conversion, as extra structural support is often needed.

Above-garage ADUs efficiently utilize vertical space but often require reinforced structures to meet safety and building codes.

The Benefits of Building an ADU

ADUs are an affordable option, but not a cheap one. Time and money are involved with any ADU construction journey, but for many homeowners, it’s a journey worth taking.

Increased Property Value

ADUs increase the value of your property, plain and simple. As for how much, it varies on the city and property itself, but recent data suggests that homes that include an ADU are priced 35% higher nationally than those without an ADU. So in the state of California, where the national average home value is around $773,239, having an ADU would increase the value to over $1.04 million. Oftentimes, this increase in value far exceeds the financial impact on property taxes and insurance.

California Bill AB-1033 also dictates that city governments can allow homeowners to sell their ADUs separately from their main home, if they so choose. San Jose is one city that has chosen to do that since the passing of the bill, and other cities may follow in the coming years.

Rental Income Potential

Though most cities still do not allow for ADUs to be sold separately from the main house, ADUs can be used as rental properties, particularly in areas like San Diego, where housing demand is high and even studio apartments can rent for over $2000.

If you are looking to build an ADU rental property, we encourage you to read this post, where we break down the construction costs, potential rental income, and ROI for an ADU build in San Diego.

View this post on Instagram

A post shared by Better Place Design & Build | San Diego ADU Builders (@betterplaceadu)

Multigenerational Living

ADUs allow families to achieve multigenerational living, even in the most densely populated cities, by providing a private space for aging parents, in-laws, or even adult children to live.

Boost property value by up to 35% with energy-efficient appliances, high-quality finishes, and flexible layouts.

What Qualifies as an ADU in California?

The state of California dictates that an ADU is an independent living space built on the same lot as a primary residence. To be considered independent, it must have a kitchen, a bathroom, and a separate entrance.

California’s ADU-Friendly Laws

In recent years, California lawmakers have encouraged ADU construction throughout the state with ADU-friendly laws. In their eyes, ADUs are not only a way to benefit existing homeowners but also a way to increase affordable housing throughout the state.

Statewide Requirements

Every city has its own requirements when it comes to ADU builds, so it’s important to work with a contractor who understands the requirements for your city. Generally, though, the maximum size limit in many cities is 1200 square feet, and the minimum is usually somewhere between 150-220 square feet.

Many cities also stipulate certain parking requirements, like providing one off-street parking space per bedroom, though these requirements may be different depending on your proximity to public transit.

Focus on Title 24 energy standards for insulation and HVAC to meet California ADU requirements.

ADU Permitting and Legal Guidelines in California

The permitting process can feel daunting to many homeowners, but the good news is that California’s recent bills have made it easier to build ADUs, and an experienced contractor can guide you through the process.

Local Zoning Laws in San Diego

Zoning laws in San Diego mostly align with state guidelines around ADU builds. For example, they are capped at 1200 square feet and must be set back 4 feet from the property line and 6 feet from an existing structure.

However, there are additional requirements and subtle differences in zoning regulations you must know when designing your ADU to get your permit approved and, ultimately, pass inspection.

Permitting in San Diego

The permitting process in San Diego, which includes the initial site review, design, document submission, and final approval, generally takes anywhere from 4-6 months.

Following construction, a final inspection is required to close the building permit and approve occupancy.

Start with a feasibility study to meet setback requirements and streamline permit approvals with detailed site plans.

Why Better Place Design & Build is Your Top Choice for ADU Projects in San Diego

Better Place has the building code knowledge and local experience you need to not only get your building permit approved but also get your project completed on time and on budget.

Reach out for a personalized consultation today. It’s completely free and will show you what’s possible for your property and your future ADU.