A guide to Berkeley ADU building regulations in California

Learn about local zoning guidelines, financing options, and getting started with building a custom ADU in Berkeley, California.

Type Five City Guide

Introduction to ADUs

A quick overview of what a backyard home offers for you, your family, and your property.

An ADU, or Accessory Dwelling Unit, is a secondary living space on your property that provides complete independence with its own living, sleeping, eating, cooking, and sanitation facilities. ADUs are also known as guest houses, in law suites, in law units, backyard cottages, and granny flats, and are built on the same lot as the primary residence or primary home. They can be attached ADUs that are connected your main house, or created as conversion ADUs by repurposing existing space, such as a garage conversion, often from existing single family homes. Alternatively, they can be built as new detached units.

There are many benefits to building an ADU, both practically and financially. It’s often more affordable than traditional homes since it leverages existing property and infrastructure, avoiding costly new developments. An ADU can provide as much living space as a modern apartment, making efficient use of your property. ADUs can provide extra income through rental opportunities, support affordable housing, and help stabilize neighborhoods by increasing housing options. They can generate rental income to offset mortgage payments, offer a private space for family members like aging parents, diversifies housing options, and increase your property’s market value. Plus, it’s eco-friendly, reducing the need for new construction and supporting sustainable living, especially in areas that are in a housing crisis.

ADUs are secondary to the primary dwelling unit and are located on the same property or same lot as the main home, providing independent living while remaining connected to the primary residence.

Key Benefits of a Backyard Home

Increases Property Value

A well-built and thoughtfully designed ADU can boost the market value of your property, often 25%- 35% higher in urban areas.

Provides Housing Options for Family Members

Creates additional space and nearby independent living for your family, regardless of their age or needs.

Expands Current Living Space

Adapts to needs like home office, guest house, or studio, and can include other spaces such as kitchens, bathrooms, or living areas.

Generates Rental Income

Provides passive income, offsetting costs or funding expenses.

Overview of ADU Construction Methods

There are a few of different ways that your ADU can be constructed

When building an Accessory Dwelling Unit (ADU), you’ll need to decide on the construction method. Common options include traditional, prefabricated (prefab), modular, and panelized construction, each with its own pros and cons. There are also several types of ADUs to consider: detached ADUs (standalone buildings separate from the main residence), attached ADUs (units built by adding onto or transforming existing structures like walls, basements, or garages), and conversion ADUs (created by converting existing spaces within a home or accessory buildings such as garages or sheds). Junior ADUs (JADUs) are smaller units, often up to 500 square feet, typically attached or converted from existing space within a single-family home, sharing some facilities and subject to owner-occupancy requirements. ADUs can also be added to a multi family building, not just single family homes.

  • Traditional Construction involves building from scratch on-site, offering high customization but often taking longer and costing more.
  • Prefabricated Construction means the ADU is built in a factory and delivered, providing speed and cost savings but with limited design flexibility.
  • Modular Construction builds sections in a factory for on-site assembly, balancing speed and customization.
  • Panelized Construction uses pre-built panels assembled on-site, offering a middle ground in cost and time.

When converting existing structures, buildings such as garages or sheds can be repurposed into ADUs, maximizing the use of your property. At Type Five, our approach combines the best of both worlds, offering you design flexibility with the cost savings and convenience of prefab. Here are some of the notable features:

  • Customizable: Every Type Five ADU is customizable online. You can select the size, color, layout, amenities, bedrooms, finishings, and more without paying thousands of dollars in design fees.
  • Turn-Key Experience: Thanks to our streamlined process, you can ditch the chaos and stress of managing the complexities of building your backyard home. We’ll draw up your plans to meet building codes, get them approved by the city, and manage construction so you don’t have to. Our platform allows us to be your project's architect and general contractor, saving you enormous time and money while giving you the peace of mind that you're getting an amazing service and product.
  • Efficient Construction Timelines: A traditionally built ADU can take dozens of subcontractors and operate under a more bespoke process to get your ADU built. We've streamlined the number of contractors involved, and run a repeatable, consistent process for every home we build. You can expect clear timelines, little to no back and forth, and weeks instead of months of construction on your property.
  • Transparent Pricing: We guarantee your price right in our design process before you even submit a deposit. You can say goodbye to financial surprises & unexpected “change orders” because every project comes with a guaranteed maximum price before the building starts. This means you can accurately budget for the other things in your life… like your retirement or that vacation you’ve been thinking about!

What’s the bottom line? If you want a backyard home but don’t want to deal with the hassle and expense of traditional construction, then prefabricated/modular construction is the way to go. And if you want the convenience of prefab with the flexibility of custom design, then we’ve got your back.

The Process

As a property owner, how an ADU gets built will vary based on who you choose as your partner, but here are the general phases. The ADU development process involves several phases, from initial planning to completion, and each ADU project is unique. Understanding the development process helps ensure your ADU development meets your goals and complies with local regulations.

Designing an ADU
01
Design
The design process is key in building a home that's tailored to your tastes, needs, and budget. This includes making decisions around the shape, size, layout, finishes, and amenities.
Estimated Timeline:
4-6 weeks
Key Milestones:
  • A site feasibility study will help determine what can be built and where.
  • Exploration and refinement of the interior layout
  • Selection of finishes and materials
  • Finalization of design plans
  • Preliminary budgets and timelines assembled for review
Who You'll Work With:
Account ManagerArchitectProject ManagerConstruction Manager
Permitting an ADU
02
Permit
In the permitting phase, the plans, applications, and documentation is compiled and submitted to the city or jurisdiction where you live. Several departments are involved in evaluating that the plans meet the local and state codes, regulations, and requirements. The permitting process is a crucial step, and submitting accurate ADU applications to the city can help streamline approvals and avoid delays.
Estimated Timeline:
2-3 months
Key Milestones:
  • Preparation of permit documentation
  • Submittal to local building department
  • Addressing any inspection comments
  • Receiving permit approval
  • Pre-construction planning
Who You'll Work With:
ArchitectProject ManagerCity PlannersBuilding Department Officials
Building an ADU
03
Build
Once the permit is approved, your project can begin construction. In a typical process, a general contractor and their team of sub-contractors will execute the different phases of the construction scope, which depends on the scale of the project.
Estimated Timeline:
4-10 months
Key Milestones:
  • Site preparation and foundation work
  • Framing and structural assembly
  • Plumbing, electrical, and HVAC installation
  • Interior and exterior finishing
  • Inspections
Who You'll Work With:
Project ManagerGeneral ContractorSkilled TradespeopleBuilding InspectorsUtility ProvidersMaterial Suppliers
Living in an ADU
04
Live
Your new backyard home is ready to live and use! Over the years, you might want to improve and upgrade your ADU.
Estimated Timeline:
Forever
Key Milestones:
  • Moving in and settling phase
  • 30-day follow-up inspection
  • Seasonal maintenance check-ins
  • Warranty service as needed
  • Future upgrade opportunities
Who You'll Work With:
Maintenance SpecialistWarranty Service TeamContractors

Skip the hassle with Type Five

Our turnkey approach makes it a breeze to avoid the complex process of designing, permitting, and building your backyard home. With us, you'll reduce costs, avoid delays, and get your project done faster.

Berkeley's ADU Regulations

Frequently asked questions about what you can build in Berkeley, based on state and local regulations.

Feasibility

Can I build an ADU on my property in Berkeley?

Yes, Accessory Dwelling Units (ADUs) are allowed in all single-family residential, multi-family residential or mixed use zoning districts. On a single-family lot, a proposed or existing single-family home is required.

How many ADUs can I have in Berkeley?

The number of ADUs you can have in Berkeley depends on whether or not your lot has a single-family dwelling (and the amount of single-family dwellings on the lot) or has a duplex or multiple-family dwelling on the lot.If you have a lot with one single family dwelling you are allowed 1 ADU and 1 JADU. If you have a lot with more than one single family dwelling you are allowed 1 ADU and no JADUs. If you have a lot with a multi-family residence, you are allowed to have up to 2 ADUs.

Design

Is there a minimum lot size for a Berkeley ADU?

There is no minimum lot size requirement. California state law also mentions that lot coverage requirements can’t preclude the creation of a statewide exemption ADU. A statewide exemption ADU is 800 square feet, with a height limitation of 16 feet and and 4 feet rear and side yard setbacks for lots with a single family home.


With Type Five, you can design an ADU to fit whatever available space you have in your backyard. Our system can flex and adapt to ensure you can build high-quality livable space even if it's in a smaller area. Get started with designing your ADU here.

Is there a minimum and maximum size for a Berkeley ADU?

Yes, there are minimum and maximum size requirements for Accessory Dwelling Units (ADUs) in Berkeley. According to the city's ADU ordinance, the minimize size for an ADU is 150sqft and the maximum size is 1,200 square feet.

Type Five's ADUs can adapt to a variety of different sizes for your need. Get started with designing yours here.

Can you build a 2 story Berkeley ADU?

It depends on on your zoning. The city of Berkeley has different height requirements for certain areas.

If your zone is within the Hillside Overlay District, the city has a maximum height requirement of 16 feet for ADUs, which means that you cannot build a 2-story ADU in Berkeley. The state of California’s building code requires a 7 feet ceiling height requirement and when you factor in the height of space needed for the floor & roof, 16 feet is typically not enough to build a legal 2 story ADU.

If your zone is outside of the Hillside Overlay District, then the city of Berkeley has a maximum height requirement of 20 feet for ADUs which means that you can build a 2 story ADU in Berkeley.

Type Five offers two-story layouts that are designed to meet the 20 foot height restriction in Berkeley.

How many bedrooms can an ADU have in Berkeley?

There is no limit to the number of bedrooms an ADU can have in the city of Berkeley according to California state law. The California HCD ADU handbook states that a limit on the number of bedrooms could be construed as a discriminatory practice towards protected classes, such as familial status, and would be considered a constraint on the development of ADUs.

How close to the property line can I build an Berkeley ADU?

All ADUs built in Berkeley and the state of California are required to have 4 feet side and rear yard setbacks. State law allows for a local government to determine its own front yard setback requirements. Berkeley requires a front yard setback of 20 feet.

Permitting

Do I need a permit for a Berkeley ADU?

You need to receive an approved building permit in order to build an ADU or JADU in Berkeley. Compliance with the ADU zoning and development standards is reviewed as part of the building permit process.

At Type Five, we take care of your entire permit process saving you time, money, and energy.

How long does it take to get a permit for a Berkeley ADU?

The maximum amount of time the city of Berkeley has to review your permit application is within 60 days of submission. It is possible to get your permit approved within 60-120 days of submission so long as your designs were drawn with the local code in mind.

At Type Five, we take care of your entire permit process. Our ADU plans meet the highest standards of construction and building code across California, ensuring that our permits are approved in the shortest time possible.

Utilities

Does an ADU need its own electrical panel, water meter, or gas meter in Berkeley?

A local agency, special district, or water company in does not require an ADU to have its own electrical panel, water meter, or gas meter in the city of Berkeley, unless the ADU was built at the same time as a new single family dwelling on the property. However, owners of ADUs that plan to be used as rental units typically install a new set of utility meters to make billing cleaner for tenants.

Are fire sprinklers required in a Berkeley ADU?

In most cases, fire sprinklers are not required in an Accessory Dwelling Unit (ADU) in Oakland. An ADU is only required to provide them if sprinklers are required for the primary dwelling unit. However, the ADU must still meet other fire safety requirements, such as minimum fire flow and water pressure on the adjoining streets.

Is solar required on a Berkeley ADU?

You may be required to install solar panels on your ADU in Berkeley if your ADU is a newly constructed, non-manufactured, detached ADU. There are exceptions to the state energy code based on floor area and climate zone. In Berkeley (Climate Zone 3), you can qualify for an exemption if the size of the ADU is no more than 1,000 square feet.

Financials

How much can I rent an ADU for in Berkeley?

You should be able to rent a Berkeley ADU for $3,164 which is the average monthly rent for a one bedroom apartment so long as the rental term is longer than 30 days. There is no owner-occupancy requirement for ADUs built prior to December 31st, 2024.

Can an ADU be used as an Airbnb or short-term rental in Berkeley?

You cannot use an ADU as an Airbnb in Berkeley unless you are renting it out for a period longer than 30 days. California law states that ADUs created under subdivision (e) of Gov. Code, § 65852.2 cannot be rented for a period less than 30 days. This means you cannot use your ADU as a short-term rental in Berkeley.

Can your HOA prevent your ADU build in Berkeley?

Your local homeowners association (HOA) cannot prohibit the construction of an ADU or JADU in Oakland. Assembly Bill 670 (2019) and AB 3182 (2020) amended Section 4751, 4740, and 4741 of the Civil Code to preclude common interest developments from prohibiting or unreasonably restricting the construction or use, including the renting or leasing of, an ADU on a lot zoned for single-family residential use.

Covenants, conditions and restrictions (CC&Rs) that either effectively prohibit or unreasonably restrict the construction or use of an ADU or JADU on such lots are void and unenforceable or may be liable for actual damages and payment of a civil penalty.

How does an ADU affect property taxes in Berkeley?

The city of Berkeley will assess the value of your newly added ADU, typically by using the cost-bases method of appraisal, and multiply it by the property tax rate of 1%. So if your ADU in Berkeley costs $217,053 to build, you can expect your annual property taxes to increase by $2,170.53 per year. Adding an ADU to your property will not trigger a reassessment of the value of your primary residence.

How much value does an ADU add in Berkeley?

Adding an ADU to your property in Berkeley typically adds value to your property, however, the exact amount depends on the appraisal method that your appraiser chooses to use. If an appraiser uses the cost-basis method & the cost of your ADU is $217,053, then you can expect your home value to appreciate by $217,053.

Another method that an appraiser can use is the sales comparison approach, where the value of the ADU addition is determined by recently sold properties in Oakland that included ADUs. However, this approach depends on the number of recently sold properties and there sometimes isn’t enough information to use this approach with ADUs. A back-of-the-envelope way to estimate the value yourself would be to multiply the existing price per square foot of your property by the square footage added by the ADU and compare it to the cost of your ADU. The appreciation is likely in between those two numbers.

How much does it cost to build a Berkeley ADU?

The average cost to build an Berkeley ADU is $217,053. Keep in mind there are a ton of factors to consider when estimating the cost of a project, many of which are unique to your property and sometimes require special surveys to identify. Examples of these factors include whether or not your property is flat or sloped and whether or not you need to upgrade your utilities.

It’s also important to note that converting an existing structure or converting your garage into an ADU isn’t necessarily cheaper than building a brand new detached ADU. You can get an in-depth overview about what goes into an ADU project in your city by starting to customize your ADU using Type Five's design tool.

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