What are the requirements to build ADU in Sonoma?
Constructing an ADU in Sonoma enables you to expand your living space and offer affordable housing for adult children transitioning to independence. To ensure the project's success, it's crucial to understand Sonoma's local regulations and thoroughly evaluate the financial aspects of construction. This guide provides comprehensive insights into Sonoma's ADU regulations and critical financial considerations, aiding you in effectively planning and executing your project.
Number of ADUs on a property
How many ADUs can you build in Sonoma?
In Sonoma, you can only construct 1 ADU on a lot with an existing or planned single-family dwelling.
How many ADUs does Sonoma allow for multifamily properties?
Multifamily properties are allowed to have at least 1 converted ADU within an existing structure, with up to 25% of the existing units being eligible for conversion in Sonoma. Additionally, a maximum of 2 detached ADUs are allowed.
Setbacks for an ADU
What are the setbacks required for an ADU in Sonoma?
In Sonoma, ADUs should maintain a minimum setback of 4 feet from side and rear lot lines, applicable to both detached and attached units. Front and street-side setbacks should conform to zoning district regulations, with detached ADUs following accessory structure setback restrictions and attached ADUs following front setback rules for primary structures.
What is the minimum distance the ADU must be from existing structures?
Most cities typically require an ADU to be at least 6 feet away from existing structures, although Sonoma hasn't specified a minimum distance.
Are setbacks required if converting existing structures into ADU?
In Sonoma, setbacks are not required for converting existing structures into ADUs.
Find out FREE if the zoning designation for your property allows you to build an ADU
The size of ADU for properties with a single-family home
How big can an attached ADU be in Sonoma?
In Sonoma, an attached ADU can be up to 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a maximum of two-bedroom unit. Development standards may reduce the size, but not below 800 square feet.
How big can a detached ADU be in Sonoma?
In Sonoma, a detached ADU can be up to 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a maximum of two-bedroom unit, similar to the requirements for single-family properties. Development standards may reduce the size, but not below 800 square feet.
Is there a minimum size of an ADU?
Yes, the minimum size of an ADU is 150 square feet.
Can you convert existing space to an ADU?
Yes, converting existing space into an ADU in a single-family property is allowed in Sonoma.
The size of ADU for properties with a multi-family home
How big can an attached ADU for a multifamily building be in Sonoma?
In Sonoma, an attached ADU in a multifamily building can be up to 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a maximum of two-bedroom unit. Development standards may limit the size, but not below 800 square feet.
How big can a detached ADU for a multifamily building be in Sonoma?
In Sonoma, a detached ADU for a multifamily building can be up to 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a maximum of two-bedroom unit. Development standards may reduce the size, but not below 800 square feet, similar to the requirements for single-family properties.
Can you stack detached ADUs on top of each other?
As of now, Sonoma hasn't addressed the possibility of stacking detached ADUs on top of each other.
Can you attach two ADUs to each other?
No, attaching two ADUs together is not allowed in Sonoma. While regulations permit up to two ADUs on a property with an existing multifamily building, they cannot be attached to each other.
Can you convert existing space to an ADU?
Yes, in Sonoma, converting existing space within a multifamily dwelling into an ADU is allowed.
The height for ADU
What is the max height for an ADU on a property with a single family house?
A detached ADU's single-story structure can't surpass 16 feet from grade to its peak, or 25 feet for a two-story ADU from finished grade to the highest roof point. Additionally, for detached ADUs, one-story walls shouldn't be higher than 12 feet above grade, and two-story walls shouldn't surpass 20 feet, with the second story's plate height not going beyond 8 feet. Attached ADUs should follow the maximum height allowed for the primary dwelling based on zoning regulations.
What is the max height for an ADU on a property with a multifamily building?
For a detached ADU, it can't surpass 18 feet on a lot with an existing or proposed multifamily, multistory dwelling. If it's a single-story detached ADU, the height limit is 16 feet above grade to the peak of the structure. For a two-story detached ADU, it can't go beyond 25 feet measured from the finished grade to the highest point of the roof. There are also specifications for wall heights: one-story walls can't be higher than 12 feet above finished grade, and two-story walls can't surpass 20 feet overall, with the second story's plate height capped at 8 feet. Attached ADUs should comply with the maximum height allowed for the primary dwelling based on zoning regulations.
Can you build a 2-story ADU in Sonoma?
Yes, you can construct a two-story ADU in Sonoma.
The parking requirements for ADU
What is the parking requirement for an ADU in Sonoma?
In Sonoma, an ADU requires 1 off-street parking spot with an all-weather surface, in addition to parking required for the main residence. Exceptions apply for ADUs within historic districts or half mile of a public transit stop, and for those integrated into existing structures.
Where can a parking space be located?
The parking space for the ADU can be located in the driveway or in tandem configuration.
Design requirements for ADU
How many bedrooms can an ADU have in Sonoma?
In Sonoma, ADUs should have a maximum of two bedrooms.
Does an ADU need a kitchen in Sonoma?
In Sonoma, ADUs usually require a full kitchen, distinct from JADUs, which may have an efficiency kitchen.
Does an ADU require independent utility meters?
For newly constructed ADUs, a separate utility connection may be required between the ADU and the utility main. However, for converted ADUs, this is typically not required.
What is the minimum ceiling height?
In Sonoma, ADUs comply with the California Building Code's requirement of a minimum ceiling height of 7 feet for habitable spaces.
Get the size of the ADU possible to build on your property after applying all these regulations
Permits for ADU
How long does it take to get an ADU permit in Sonoma?
Getting an ADU permit in Sonoma typically involves a ministerial process without discretionary review or a hearing. The city aims to approve or deny ADU permit applications within 60 days of receiving a completed application. However, this timeline may be extended if the applicant requests a delay, during which the 60-day period is put on hold.
When do you need a licensed professional to design an ADU in Sonoma?
For optimal design of an ADU in Sonoma, it's advisable to consult with a licensed professional such as an architect or engineer, especially if considering unconventional construction methods.
Does Sonoma require in-person submission of plans for an ADU?
No as electronic submission of plans for ADUs in Sonoma eliminates the need for in-person submissions.
Does Sonoma require coastal development permits?
Yes, properties located in the Coastal Zone are subject to additional development procedures. Approval from the California Coastal Commission through a Coastal Permit processed by Permit Sonoma is necessary for any land use within this zone.
Economics of ADU
How much does it cost to build an ADU in Sonoma?
Constructing an ADU in Sonoma typically costs around $380 per square foot, covering expenses like permits, architectural design, and engineering services. For instance, building a 900-square-foot ADU would cost about $390,000, including both soft and hard costs.
Is it profitable to build an ADU in Sonoma?
Determining the financial feasibility of constructing an ADU in Sonoma involves comparing construction costs with local real estate market values. For example, a 900-square-foot ADU could potentially be valued at approximately $650,000. With construction costs at $390,000, this suggests a potential return on investment of around 70%.
Other factors contributing to profitability may include potential rental income or the advantages of accommodating family members on the same property.
Can you sell an ADU in Sonoma?
In Sonoma, it may be allowed to sell an ADU under state laws like AB 1033, which enable potential sales or conversions into condominiums, potentially requiring the establishment of a Homeowner Association (HOA) for management purposes.
Are ADUs rent controlled in Sonoma?
In Sonoma, ADUs are not under rent control measures. Landlords have the flexibility to adjust ADU rents annually, typically in accordance with regulations like AB 1482, which commonly affect properties aged 15 years or older.
How to get money to build an ADU in Sonoma?
Securing funds for ADU construction in Sonoma can involve exploring avenues such as the CalHFA’s ADU Grant Program, which provides grants of up to $40,000. These funds cover expenses like architectural designs, permits, and site preparation, aiding in the advancement of ADUs as a viable affordable housing option in the area.