ADU Resources

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. Also known as granny flats, in-law units, or backyard cottages, ADUs provide independent living spaces with their own kitchen, bathroom, and sleeping areas.

ADUs can be detached structures in your backyard, converted garages, or additions to your existing home. They offer flexible housing solutions for family members, rental income opportunities, or home office space.

In San Diego, ADUs have become increasingly popular as a way to address housing needs while maximizing property value.

San Diego has specific regulations governing ADU construction. The city allows ADUs on most single-family residential lots, with size limits typically based on your lot size and existing home.

Key regulations include: maximum size of 1,200 square feet for detached ADUs, minimum setback requirements (typically 4 feet from rear and side property lines), and height restrictions (usually 16 feet for detached units).

The city has streamlined the permitting process for ADUs that meet standard requirements, making it easier than ever to add this type of housing to your property. For detailed information, visit the City of San Diego ADU Information Bulletin.

To look up the specific zoning for your property, use the San Diego Zoning Map. This interactive tool lets you search by address to see your lot's zoning designation and applicable regulations.

ADUs can be built for under $300 per square foot, though many factors can make that number go up. Site conditions, material choices, finishes, and design complexity all impact the final cost. Garage conversions are generally less expensive than new detached structures.

Factors that can increase costs include: challenging site preparation, utility connections, foundation requirements, premium materials and finishes, permit fees, and custom design elements. A detailed feasibility study helps establish realistic budget expectations for your specific property.

Financing options include home equity loans, construction loans, cash-out refinancing, and specialized ADU loan programs. Many homeowners find that rental income from the ADU helps offset construction costs over time.

The typical ADU project takes 8-14 months from initial consultation to move-in ready. This includes design (2-3 months), permitting (2-4 months), and construction (4-7 months).

The process begins with a feasibility study to assess your property and goals. Next comes design development and permit preparation. Once permits are approved, construction begins with site preparation, foundation, framing, and finishing work.

Working with an experienced design-build firm streamlines the process by coordinating all phases under one roof. This integrated approach reduces delays and ensures quality control throughout the project.

ADUs offer multiple benefits for homeowners. They can generate rental income (San Diego ADUs typically rent for $1,500-$3,000/month), provide housing for family members, or serve as a home office or studio space.

Property value typically increases by more than the construction cost, making ADUs a sound investment. They also offer flexibility—use it as you need it now, with options to change its purpose later.

ADUs contribute to housing availability in San Diego while allowing you to maintain your single-family home character. They're an environmentally friendly way to increase density without new land development.

Good ADU design balances functionality, aesthetics, and budget. Consider how the unit will be used—rental, family housing, or personal space—as this affects layout and features.

Key design elements include: efficient floor plans that maximize space, natural light through strategic window placement, storage solutions, and outdoor access. The ADU should complement your main house while having its own identity.

Practical considerations include parking requirements, utility connections, privacy for both units, and future flexibility. A well-designed ADU feels spacious and comfortable despite its compact size.