STATEWIDE UPDATE: New California ADU Bills SB13, AB68, AB881, AB670 have passed. These laws will create more options for building an ADU in Mountain View in 2020. To prepare for the upcoming changes use our ADU Services to learn how these laws will effect your property!
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Last Updated 08/11/19


The city government of Mountain View has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2016 is adopted with the following amendment(s): MountainView17.16and18.16 CALGreen
Relevant state bill updates for SB13, AB68, AB881, AB670 are shown in green below.


City Hint: The city has not yet responded to requests for ADU permit volumes for the past year, but they will be provided here once response has been received.


Number of ADUs allowed:

One ADU per parcel.

AB68 & AB881 Update: Properties which convert existing space to create ADUs may be eligible for one ADU -AND- one JADU.

Types of ADUs allowed:

Detached ADU, attached ADU, junior ADU.

Lot size:

No minimum lot area required.

AB68 & AB881 Update: Properties will not be subject to minimum lot standards by ordinance or of the applicable zoning district.

ADU size:

700 square feet of habitable floor area, maximum, and 200 square feet for a garage, maximum, provided the total floor area for the lot does not exceed the maximums allowed for the R1 zoning.

AB68 & AB881 Update: Properties will be allowed up to 850 square feet for a one bedroom or up to 1,000 square feet for a two bedroom ADU.


Side: 1‐story detached structure: 5 feet minimum, 12 feet Total. Single‐story attached (basement): comply with required setbacks of the main house. A 2‐story over attached or detached garage: See Sec. 36.10.25 for 2nd story setbacks. Rear: 1‐story detached: 10 feet minimum. 1‐story attached (basement): comply with required setbacks of the main house. See Sec. 36.10.25. 2‐story over attached or detached garage: See Sec. 36.10.25 for 2nd story setbacks. Interior: Interior 10 feet minimum, from primary dwelling or other Structure, if detached.

AB68 & AB881 Update: The maximum required setback for a detached new construction ADU shall be no more than 4 feet from the rear or side property lines.


Required Spaces: 1 space per unit, which can be covered or uncovered.
Shared Parking: A driveway, garage or carport may be shared with the primary dwelling unit if the ADU has direct, unobstructed (or shared) access to the parking space(s).

AB68 & AB881 Update: Properties which convert an existing garage will not be subject to replacement parking requirements.

Fire Safety:

Per state requirements.

Shape, materials and style:

The design of the unit shall conform in general to the design of the primary dwelling.


1‐story detached: 16 feet maximum building height and 9 feet at top of the wall plate. 1‐story attached: See Sec. 36.10.25 for height limits for principal structures. 2‐story (over garage): 28 feet maximum building height and 22 feet at top of wall plate.

Design review:

Ministerial review process.

Number of Bedrooms:

Not specified by State Standards.


Unit is not intended for sale separate from the primary residence and may be rented. (State requirements)

SB13 Update: Owner-occupancy requirements for ADUs will be voided statewide for 5 years.

Utility connections:

Local health officer approval where a private sewage disposal system is being used, if required. (State requirements)

Allowed Zones:

An accessory dwelling unit may be allowed on a lot occupied with a single-family
dwelling unit in the R1 zoning district in addition to a primary dwelling

AB68 & AB881 Update: ADUs will be allowed statewide in all single-family or multi-family zoning districts.

Existing Structures

Conversion of an accessory structure/garage or other living space to an
accessory dwelling unit shall meet all adopted building codes for residential occupancy.
Such conversions shall also require a ministerial review or a hearing within one
hundred twenty (120) days after receipt of a substantially complete application.

SB13 Update: Amnesty program to permit unpermitted units will be administered statewide, allowing non-health and safety code violations to be deferred.


1) Attached to a principal structure - Basement, ground level or above the garage with
no internal access to the primary dwelling. 2) Detached unit - Rear half of lot. 3) Above a detached garage - Rear half of lot.

Residential Building Code:

The California Building Code (CBC) 2016 is adopted with the following amendment(s): MountainView17.16and18.16 CALGreen

Mountain View City Planning Offices

City of Mountain View Planning Department

Diana Pancholi

500 Castro Street Mountain View, CA 94041 Mountain View, CA 94041

Featured LenderFinancing

Nikki James

Opes Advisors

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Mountain View ADU Marketplace

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Karyn Jones

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Call Now (760) 496-5959

Read Mountain View Housing Market Update

Featured ArticleMountain View, CA
Featured ArticleState of CA

What are Accessory Dwelling Units? California Department of Housing and Community Development 2017-05-15

Featured ArticleState of CA

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Costs / ROI


* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $5.28) * (ADU's Living Space: sqft)

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