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Berkeley, California

Berkeley has updated its ADU ordinance to comply with new state laws. Read the up-to-date requirements & what to watch out for when building an ADU in Berkeley.

Updated Sep 15, 2023

Berkeley, CA

According to the City of Berkeley's Planning & Building Department, a total of 161 ADUs were permitted in Berkeley in 2022. This is a significant increase from the 80 ADUs permitted in 2021. The increase is due to a number of factors, including the city's ADU incentive program, which provides financial assistance to homeowners who build ADUs.

General ADU Requirements

The requirements for ADUs in Berkeley vary depending on the type of ADU and the location of the property. Berkeley defines the types of ADUs as:

Standard ADU (i.e. detached, attached, or conversion ADU): An attached or detached secondary dwelling unit that contains permanent places for living, sleeping, and cooking.
Junior ADU (JADU): A secondary unit that is contained within the habitable floor area of a single-family residence. It may share a bathroom with the existing home but must have it’s own exterior access.

ADU kitchens must also have:

A sink with running water
Countertops and cabinetry of a reasonable size
A refrigerator
A permanent range/cooktop that doesn’t need more than 120V or natural/propane gas

Zoning

All properties zoned for residential use, including both single family and multi-family may be eligible to build ADUs. Lots in Berkeley’s Hillside Overlay zones (R-1H, R-2H, R-2AH, and ES-R only) may have more stringent zoning requirements for ADUs.

Fees

Impact fees are waived for ADUs less than 750 sq. ft. Utility and connection fees are waived for JADUs and conversion ADUs in single family properties. In our experience, plan check and building permit fees total around $5,000 to $10,000 for an average ADU in Berkeley.

Number of units

The number of ADUs you’re able to build in Berkeley depends on how your lot is zoned:

Lots zoned for single family use may add 1 ADU and 1 Jr. ADU (JADU).
Lots zoned for multi-family may add 2 new detached ADUs and at least one conversion ADU (interior conversion of existing building, but no more than 25% of the original number of units. (E.g. an apartment with 4 units may add 2 detached ADUs and 1 conversion ADU.)

Building size

The maximum ADU you can build in Berkeley depends on your zoning and ADU type:

JADUs may reach a maximum of 500 sq. ft.
Maximum height for studio or 1 bedroom ADUs is 850 sq. ft.
Maximum height for 2+ bedroom ADUs is 1,000

Building height

The maximum height you can build depends on your ADU type:

New construction detached ADUs have a maximum height of 20 ft.
New construction attached ADUs have a maximum height of 25 ft. Attached ADUs must comply with the height requirements of the applicable zoning district.
Conversion ADUs are limited to the height of the existing structure in Berkeley.

Note that lots in Hillside Overlay zones may have lower maximum allowable heights.

Basements

Existing unfinished basement space can be used for a conversion ADU.

Setbacks

The minimum setback from the rear and side lot lines in Berkeley is 4 ft. The minimum setback from existing structures is 3 ft., however with less than 5 ft. of clearance additional fireproofing may be required.

Chimneys, water heater enclosures, flues, heating and cooling equipment, eaves, cornices, canopies and awnings may project 2 ft. into the required setbacks, so long as there remains at 2 ft. from the property line. Berkeley does not allow bay windows and balconies to enter the required setbacks.

Parking

No additional parking is required for ADUs. Even when converting a garage or carport, replacement parking is not required.

Owner-occupancy

Owner occupancy is not a requirement for permitting an ADU from January 1, 2020 until January 1, 2025. This is a great opportunity for rental property owners to increase their yields in a cost-effective way.

Rental

While long-term rentals are permitted for ADUs, short-term rentals (e.g. Airbnb for less than 30 days) are not permitted in Berkeley.

Fees

Impact fees are waived for ADUs less than 750 sq. ft. Utility and connection fees are waived for JADUs and conversion ADUs in single family properties.

Watch-outs

Do you have a utility easement over your property? Do you have special setbacks? Reach out to us and we’ll help you build a custom ADU to fit your unique property characteristics and local regulations!

FAQs

How close to my house can I build an ADU in Berkeley?

When building a detached ADU in Berkeley, it should be at least 3 ft. away from your primary residence, but below 5 ft. may require additional fireproofing for the ADU. You cannot build a detached ADU in front of a single-family primary residence or within the front setback area of a multi-family home. It is a good idea to check such requirements with local authorities before starting your project.

Can I convert my garage into an ADU?

Yes, if you own a single-family home in a residential-zoned area, you may convert your garage into an ADU. Depending on the condition that your garage is in, the project may take under 9 months to complete and cost less than building a detached ADU. Reach out to our team to get an assessment on the condition of your garage and whether it can be converted affordably.

What is the smallest ADU I can build in Berkeley?

Across California, the smallest ADU you may build is 150 sq. ft., regardless of type.

Does an ADU need a kitchen in Berkeley?

Yes! ADUs in Berkeley must accommodate permanent and independent living, and be equipped with a fully functional kitchen, including 1) a sink, 2) a refrigerator of at least 10 cubic feet, and 3) either a cooktop and an oven or a range.

JADUs in Berkeley must have an ‘efficiency kitchen’, which includes 1) a sink, 2) appliances (microwave, toaster, oven or hot plate); 3) a food preparation counter.

Can I build 2 ADUs on my property in Berkeley?

If your property is zoned for single-family living, then you may be eligible to build one ADU and one Jr. ADU (JADU). Multi-family properties in Berkeley may be able to build more detached and conversion ADUs, based on the number of dwelling units already on the property. Reach out to our team for an assessment on how many.

What is the difference between an ADU and a JADU?

ADUs may either be attached to or detached from the primary dwelling, while JADUs are contained entirely within the primary dwelling. ADUs must be equipped with permanent facilities for independent living, but JADUs need only have an “efficiency” kitchen and may share some facilities with the primary dwelling. The maximum size allowed for a JADU is 500 sq. ft., while two-bedroom ADUs in Berkeley may be up to 1,000 sq. ft.

How much does an ADU increase property taxes in Berkeley?

Thankfully, your existing property will not be reassessed if you build an ADU in Berkeley!

You can expect the value of your property to increase after you build your ADU. Since property taxes are often based on property values, this can increase your property taxes. However, any increases will only be based on the value of the ADU itself. Building an ADU will not trigger a reassessment of the value of your main home.

How many bedrooms can an ADU have in Berkeley?

There’s no explicit limit to the number of bedrooms for an ADU in Berkeley, however at the maximum allowable size of 1,000 sq. ft., you’d generally be able to fit 2 nicely sized bedrooms or 3 smaller ones if you get creative.

How long does it take to build an ADU in Berkeley?

The entire process, from start to finish, would depend on the type of ADU you’re building, the scope of your project, and the area you’re building in. In our experience in Berkeley, the permitting timeline ranges from 3-6 months. Our fastest yet was 81 days!

Can I rent my ADU in Berkeley?

Yes, many homeowners we’ve worked with in Berkeley rent out their ADUs, given the high demand for housing and high rents. Short-term rentals of less than 30 days are not allowed in Berkeley, but you can rent out your ADU on platforms like Airbnb for 30+ days.

How many square feet can an ADU be in Berkeley?

Depending on zoning conditions, setbacks and the number of bedrooms you are hoping to include, you may be allowed to build an ADU that has a maximum area of 1,000 sq. ft.

Can you build a 2-story ADU in Berkeley?

It is possible to build a two-story ADU in Berkeley, given the newly updated maximum height of 20 ft. for a detached ADU and 25 ft. for an attached ADU.

Do I need solar on my ADU in Berkeley?

Solar requirements for ADUs were updated for 2023. As of 2023, ADUs below 1,000 sq. ft. (which is currently all ADUs in Berkeley) are likely exempt from solar requirements. All conversion ADUs are exempt from solar requirements.

Want to learn more about ADU regulations in your area?

Book a free consultation and estimate with a Cottage ADU Expert to find out what’s possible on your property!