Accessory Dwelling Units (ADUs)
Banner photo credit: Valley Home Development Corp. & Prefab ADU
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Want to expand your home or add a new living space? Accessory Dwelling Units (ADUs) can be a great option! This page will help you understand what ADUs are, the types available, and how to start your project.
What is an ADU?
An Accessory Dwelling Unit (ADU) is a small, self-contained home on the same property as a Single-Family or Multi-Family residence. ADUs include everything needed for independent living, like a kitchen, bathroom, and sleeping area.
Here in Oakland, ADUs cannot be rented for short-term stays (less than 30 days). ADUs come in different types based on where they are built and how they are constructed.
Types of ADUs
ADUs for Single-Family Homes
If you have a Single-Family home, you can add an ADU in one of three ways:
- Junior ADU (JADU) – Converts existing space inside your home (like a bedroom or garage) into a small unit (500 sq. ft. max). Requires the owner to live on the property.
- Category One ADU – Converts or rebuilds an existing space (like a garage or basement). No expansions are allowed, except for a small entrance (up to 150 sq. ft.).
- Category Two ADU – Builds a new attached or detached structure on the property.
Explore ADUs on Lots with Single-Family Homes
ADUs for Multi-Family Homes
If you own a Multi-Family building (duplex, apartment, etc.), you may be able to add ADUs in different ways:
- Category One ADU – Converts non-living spaces (such as storage rooms, attics, or garages) into housing.
- Category Two ADU – Builds new detached ADUs or converts existing detached structures into ADUs.
- Category Three ADU – Creates one new ADU by converting or attaching an ADU to the primary building. No other ADUs are allowed on the lot if this option is chosen.
Explore ADUs on Multi-Family Lots
Pre-Approved Plans
Oakland offers pre-approved ADU building plans for easier and faster approval. These plans meet the latest building codes and are available for Studio, One Bedroom, or Two-Bedroom dwellings.
Benefits of Pre-Approved Plans:
- Faster approval process
- Lower permit fees
- Potential cost savings
Is an ADU Right for You?
ADUs offer many benefits for homeowners, renters, and communities, such as:
Extra rental income for homeowners
More housing options for family or friends
A smaller environmental footprint
Helping solve the housing crisis
Creating flexible living spaces
Can you Build an ADU?
Most residential lots allow ADUs, but some restrictions apply, especially in high-fire risk areas or commercial zones. [Check Your Zoning Requirements]
How Much Does an ADU Cost?
The cost of an ADU depends on its type, size, and materials.
ADU Types & Cost Per Square Foot (Estimates)
- Convert existing space (garage, basement): $200-$300 sq/ft
- Convert existing accessory structure: $300-$650 sq/ft
- Add to an existing home: $250-$400 sq/ft
- Build a new detached ADU: $300-$500 sq/ft
- Prefabricated (modular) ADU: $300-$500 sq/ft
State & Local Codes
ADUs must follow state and local building codes, including:
Design & Apply for Your ADU
Design Your ADU:
- Use Pre-Approved Plans – Faster approval with city-approved designs.
- Modify a Pre-Approved Plan – Customize an existing design.
- Hire a Professional – Work with an architect or contractor experienced with Oakland permits.
California encourages ADU construction, making the permit process faster than most home projects.
Your application has two main steps:
1. Zoning Approval – Ensures the ADU meets location, size, and height requirements.
2. Building Permit – Verifies that the ADU is built safely and meets Building Codes.
Follow any of the button links below for details on each type of ADU shown.
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We’re here to help! Contact us for information on permits, costs, and requirements.
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Call us:
- (510) 238-3891 (Building)
- (510) 238-3911 (Planning/ Zoning)
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