Build an ADU in Santa Rosa, California

Browse ADU plans, match with builders, and learn what you can build in Sonoma County
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Overview

Santa Rosa is located in Sonoma County in California. Santa Rosa has a total
population of 167815 over a land mass of 41.29 Square Miles. When it comes to
ADUs, the city allows for 1+ ADUs on a given property, and a square footage of
850-1,000 sf

Number of ADUs Allowed

1+

Size of ADU Allowed

850-1,000 sf

Types of ADUs Allowed

Detached, Junior, Attached

Permit Cost

Coming Soon

Number of ADUs allowed

Under state law, each single-family home may now build at least one ADU. Owner
occupied single-family parcels may build one ADU and one Junior ADU.
Multi-family parcels, per every four existing residential units, may build one
ADU, so long as the existing units were legally established.

Property Requirements

Single-family and multi-family Parcels will be permitted to add up to 850 sq.
ft. for a one bed ADU or up to 1,000 sq. ft. for a two bed ADU, regardless of
the underlying zoning standards of the property. A Junior ADU up to 500 sq. ft.
is permitted. The minimum size of any living unit (including ADUs and Junior
ADUs) is 150 sq. ft. according to Califronia Residential Code. ~ According To
AB68

Types of ADUs Allowed

Attached ADU

An attached ADU is one that is attached to your house. Also know as Addition ADUs or “bump-out ADUs. These types of ADUs can be accessed from the primary house with a door in the connection point, but also can be independent of the main home.

Detached ADU

A detached ADU is not connected to your primary house. The dwelling needs to be within your property setbacks and allowable building size (both height and square footage).

Junior ADU

Junior Accessory Dwelling Units (JADUs) are named this way because they are small (up to 500 square feet).

In California, the recent state bills AB68 and AB 881 permits both an ADU and a Junior ADU (JADU) on the same lot with a proposed or existing single-family dwelling. This means you can have two units on your lot: ADU, and JADU.

Property Requirements

Ownership
Between between 2020 and 2025, owner occupancy requirements will not apply to
new Accessory Dwelling Unit (ADU)s. (applicable to new construction and
conversion units) ~ SB-13
Number of ADUs Allowed
Under state law, each single-family home may now build at least one ADU. Owner
occupied single-family parcels may build one ADU and one Junior ADU.
Multi-family parcels, per every four existing residential units, may build one
ADU, so long as the existing units were legally established.
ADU Size
Residential properties will not be subject to any minimum lot size for ADUs by
ordinance or of the underlying zoning district. ~ According To AB68
Parking
Replacement parking shall not apply to parcels which convert an existing garage
to an ADU or Junior Accessory Dwelling Unit. ~ Updated: State Law AB-68
Height
Height limit. A one-story accessory dwelling unit shall not exceed a maximum
height of 16 feet. A two-story accessory dwelling unit shall not exceed a
maximum height of 27 feet.
Fire Safety
An automatic fire sprinkler system shall be installed throughout the buildings
that exceed 1,200 square feet GROSS floor area. An automatic fire sprinkler
system shall be installed throughout all buildings that undergo any combination
of substantial remodel, addition, or both that exceed 50% of the existing GROSS
floor area.
Utility Connections
Utility Connection Fees. Except as provided in subsection (b), a separate new
utility connection and payment of a connection fee or capacity charge pursuant
to State law and City fee schedule will be required for any new accessory
dwelling unit. No new or separate utility connection or related connection fee
or capacity charge will be required for accessory dwelling units that are
internal conversions of existing space within a single family residence or an
accessory structure. Utility Connection Fees. No new or separate utility
connection and no connection fee for water sewer, or power is required for a
junior accessory dwelling unit.
Aesthetic
Architectural compatibility. If visible from a public street, an accessory
dwelling unit shall incorporate the same or substantially similar architectural
features, building materials and colors as the primary dwelling unit or
compatible dwellings located on adjacent properties.
Set backs
The maximum required setback for a detached new construction ADU shall be no
more than 4 ft from the rear and side property lines. Setbacks will not be
required for ADUs and JADUs converted from existing space that was legally
eastablished. Attached ADUs and conversions from existing space to be expanded
will be required to comply with the setbacks of the underlying zone. ~ AB-68

Design Review

Permit requirements. An application for an accessory dwelling unit that complies
with all applicable requirements of this Section shall be approved . Permit
requirements. An application for a junior accessory dwelling unit that complies
with all applicable requirements of this Section shall be approved .

Next Steps

To get started on your ADU, here are some first steps.

Call Your City

Search Google for your city’s contact number. eg “City of {Phoenix} Residential Permits Contact Number”

You can call the main line and get directed to the permitting department.

Ask these questions...

1) Can I put a secondary home on my lot (Accessory Dwelling Unit)?
2) What are my livable setbacks, and ADU size regulations?
3) Can I put a prefabricated guest house on my property?

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