How Much Does It Cost to Build an ADU in San Diego?

Adding an accessory dwelling unit (ADU) to your property is beneficial, as it can add living space to accommodate family members or provide passive rental income. When considering the cost of building an ADU in San Diego, you have to assess more than just the cost of construction, as there are many other expenses associated with it.

What Is the Average Cost of Building an ADU in San Diego?

The total cost of building an ADU depends on the size, design, construction, and degree of finishes used. For context, building a new ADU involves building a foundation, walls, roof, insulation, plumbing system, electrical system, and interior finishes, among other things. For these reasons, it is often considered cheaper to convert an existing structure like a garage or another viable area as opposed to constructing a new dwelling, assuming that the existing structure is in good shape.

The cost of construction will vary depending on the level of customization and quality of finishes. Instead of relying on just one average, it is better to get a personalized estimate.

What Factors Affect ADU Construction Cost?

Many factors will determine the final ADU construction cost:

  • Size and layout: Bigger dwellings generally cost more to build, but they may have a reduced cost when comparing the cost per square foot.
  • Site preparation: Surveying, soil testing, grading, excavating, and other preparation requirements are needed prior to construction.
  • Utilities: Utility hookups such as water, sewer, gas, and electricity should be professionally installed to pass inspection.
  • Building materials and finishes: The cost of cabinetry, counters, floors, fixtures, and other items can vary depending on the quality.
  • Design and permits: Architectural plans, engineering, and city permits costs can vary based on the size of the project and the city it is being completed.


When factoring in the cost of constructing an ADU, it’s always better to plan for every possible cost in advance to avoid any unpleasant surprises and keep your project aligned with your budget.

Why Building an ADU in San Diego Is Different

When it comes to constructing an ADU in San Diego, there are local factors that need to be considered. To start, the condition of all properties differs from one to another based on environmental factors. For example, a property located near the ocean will have different considerations than a property located near hills and canyons. This is because of added precautions such as fire and flood risks. The potential of these environmental factors will call for additional permits or construction processes.

Permits in general are a matter of their own. The City of San Diego requires that property owners get a building permit for all ADU construction projects. The fees vary based on the size of the project and zone restrictions.

How to Plan Your ADU Construction Budget

Your budget should include more than just the cost of construction. You should also factor in permit costs, architectural design and engineering costs, land preparation, utility hookups, finishing work, and contingency for unforeseen costs.

Working with a contractor that specializes in ADU construction in San Diego County can help you budget properly by evaluating your property, recognizing any potential problems, and choosing suitable designs before the project takes place.

It is also important to think about how you intend to utilize the unit. For example, a rental property will require a functional and maintenance-free design, while an ADU to house family members may require fewer features.

Build Your ADU with D&L Builders

Constructing an ADU can offer a great opportunity for you to create more living space within your existing property while also increasing your property value for years to come. Working with a contractor who knows city requirements can save you plenty of headaches down the road. A well-established contractor can provide an estimate that includes permits, designs, planning, construction, and utility hookups, which in turn gives you a realistic budget for your project.

Looking for an estimate to build an ADU on your property? Let us guide you through the process. We manage all aspects of ADU construction to provide you with a proper estimate of your dream project. Take the first step and contact D&L Builders today to schedule a consultation.

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