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Sunnyvale, California

Sunnyvale ADU Requirements: Sunnyvale has updated their ADU ordinance to comply with new state laws. Below are the up-to-date ADU requirements.

Updated Apr 04, 2023

Sunnyvale’s ADU ordinance is in line with state laws, making it easier to get your ADU project up and running! Here’s a quick look at the requirements for building an ADU in Sunnyvale.

General ADU requirements

While single-story standard ADUs (detached, attached, conversion) and Junior ADUs (JADUs) are permitted, JADUs must be converted out of existing living space.

Standard ADUs must be equipped for independent living and have permanent facilities for:

Living
Eating
Sleeping
Sanitation
Cooking
Exterior access that is separate from the primary dwelling

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

JADUs may share bathroom/sanitation facilities with the primary dwelling, but they must have a separate entrance. Conversion ADUs must also have their own entrance.

Zoning

All properties zoned for single-family or multi-family with the following zoning codes are eligible for ADUs. Check the zoning of your property here:

R-1 (most single-family homes)
R-2, R-E, R-M, RMD (duplexes & multi-family)
OS (open space) when single-family residential is a permitted land use
PC (planned community when single-family residential is a permitted land use

There is no minimum lot size for residential properties to build ADUs.

Fees

During the course of building your ADU project, you can expect to pay the following fees:

Building Permit Fees
Land Development Fees
Planning Permit Application Fees
Development Impact Fees

The cost of getting a Building Permit would depend on the value of your property and would dictate the cost of getting a Plan Check and other processes.

Land Development Fees constitute the cost of setting up a water connection, sewage connection, storm drainage, and other developmental services.

Similarly, the other fees are also dependent on the specific needs of your property and the scope of your project — our experts can help you figure out all the costs involved at the start of your project.

Permit types

Depending on the specifics of your Standard ADU (SADU) project, you can get either a Streamlined or Non-Streamlined permit.

1) Streamlined SADU Permits

Streamlined SADU Permits only come with a Building Permit and have the following requirements for detached SADUs and conversion SADUs to be eligible:

Detached SADUs

Cannot be larger than 800 sq. ft.
Must have side and rear setbacks of 4 ft
Can have a maximum height of 16 ft

Conversion SADUs

No maximum size
Can include 150 sq. ft. of new construction if ingress/egress modifications are required

2) Non-Streamlined SADU Permits

They include both the Building Permit and the Planning Permit and have the following requirements:

SADUs larger than 800 sq. ft. must abide by all development standards pertaining to lot coverage, required rear yard encroachment, architectural review, etc.)
Detached SADUs above 800 sq. ft. require a Miscellaneous Plan Permit (MPP)
Attached SADUs involving construction more than the 150 sq. ft. allowed for ingress/egress modifications also require an MPP
SADUs being built at the same time as a single-story single-family home require a Design Review
Second-story ADUs requiring new construction must also submit to a Design Review and provide written notice to all neighbors within 300 ft

Number of units

All single-family homes are allowed to build at least one ADU. If the single-family home is owner-occupied, it may house one ADU and one Junior ADU (JADU).

Multi-family properties with existing dwelling structures may house up to two detached ADUs or conversion ADUs. The number of ADUs cannot exceed 25% of the number of existing dwelling units on the multi-family property.

Building size

ADUs must be at least 150 square feet in size. The maximum size is 500 sq. ft. for a JADU, 850 sq. ft. for a one bedroom ADU or 1,000 sq. ft. for a 2+ bedroom ADU. Attached ADUs cannot be greater than 50% of the existing home’s floor area.

Building height

Detached ADUs can reach a maximum height of 16 feet. Attached ADUs can reach the same height as the main structure, assuming they comply with municipal code (including daylight plane).

Basements

Conversion of existing unfinished basement space can be used for an attached ADU.

Setbacks

Detached ADUs must be setback from the primary dwelling by 10 ft and must be setback 4 ft from the side and rear lot lines. If a structure was demolished to allow the construction of an ADU in that same location and according to the same dimensions, that ADU may have side and rear setbacks of less than 4 ft.

Conversion ADUs and JADUs must be setback enough so fire safety isn’t hindered. Along with this, external entry points cannot be constructed on a street-facing building elevation, regardless of ADU type.

Parking

No additional parking is required for ADUs if:

The ADU is located within one-half mile walking distance of public transit
The ADU is located within an architecturally and historically significant historic district
The ADU is part of the proposed or existing primary residence or an accessory structure
On-street parking permits are required but not offered to the occupant of the accessory dwelling unit
There is a car share vehicle located within one block of the accessory dwelling unit with a designated pick-up/drop-off location

If an existing parking space was lost to accommodate a conversion ADU, that parking space should be replaced.

Should you decide you want to build additional parking, covered parking provided for the ADU is included in the total floor area for the site, but not included in determining the max size for the ADU.

Fire safety

You are not required to install a fire sprinkler system in your new detached ADU if it wasn’t required in your primary dwelling.

If you are building an attached ADU, you may be required to install a fire sprinkler system if:

The attached ADU has a living space that is 50% larger than the primary dwelling
The primary dwelling has an existing fire sprinkler system

Utility connections

Separate utility connections aren’t required for conversion ADUs but detached ADUs may require a new direct utility connection. Connection fees and capacity charges depend on the burden of the proposed ADU, its size, and plumbing fixtures. Attached ADUs may connect to the existing utility systems. Both attached and detached ADUs require their own heating systems.

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.

Having said that, if a JADU is being built, then either the JADU itself or the primary dwelling must be owner-occupied.

Rental

While long-term rentals are permitted for ADUs, short-term rentals for under 31 days (e.g. Airbnb) are not permitted in Sunnyvale.

Watch-outs

Do you have a utility easement over your property? Are you on a lot with special setbacks? A custom ADU might be right for you. 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 Sunnyvale?

When building a detached ADU, it should be at least 10 ft away from your primary residence. 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.

What is the smallest ADU I can build in Sunnyvale?

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

Does an ADU need a kitchen in Sunnyvale?

Yes! ADUs must accommodate permanent and independent living, and be equipped with a fully functional kitchen.

Can I build 2 ADUs on my property in Sunnyvale?

If your property is zoned for single-family living, then you may be eligible to build one Standard ADU (SADU) and one JADU. Multi-family properties may house up to two SADUs or conversion ADUs, but this may vary based on the number of dwelling units already on the property.

What is the difference between an ADU and a JADU?

ADUs (or SADUs) 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 may be up to 1,000 sq. ft.

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!