Accessory Dwelling Units

An accessory dwelling unit (ADU), also referred to as a companion unit or in-law unit, is a dwelling unit that provides complete, independent living facilities on the same lot as a single-family or multi-family dwelling.

Independent living facilities include permanent provisions for living, sleeping, eating, cooking and restroom facilities. ADUs can be attached or detached from the main dwelling unit(s) on-site. An ADU of 500 square feet or less in size with an efficiency kitchen, with or without a bathroom, is called a junior accessory dwelling unit (JADU) and is allowed within the single-family home.

A permit is required to create a new accessory dwelling unit or junior accessory dwelling unit, which must be obtained prior to the start of construction work. The following is required to be submitted:

1. A complete set of electronic building plans compiled into one PDF file (see Requirements below).
2. A completed Mountain View Green Building Residential Worksheet, which must be integrated into your building plans.
3. Include any project manual and specifications. 
4. Provide structural calculations.
5. Provide energy calculations in the building plans.
6. Include electrical load calculations with submittal. If a new electrical submeter is proposed for an ADU, the minimum size is 125 amp panel per City Code Section 8.51(D). 
7. Title Report (or recent grant deed showing current ownership). Note: For a JADU, a current grant deed is required to be submitted in order to prepare a covenant. 
8. A site survey prepared by a licensed civil engineer or land surveyor is required for structures within 6’ of a property line or required setback. You must provide a site survey certificate and obtain approval from the City prior to the concrete pour for the foundation or footings. Present the wet-signed certificate to City Building Inspector for verification at site inspection.
9. Provide a completed Change of Address Request Form.

Before preparing detailed building plans, we encourage you to review preliminary designs of your ADU or JADU with the Planning Division at 650-903-6306 or planning.division@mountainview.gov.

Permit Required

A building permit (including electrical, mechanical, plumbing) and a demolition permit are required. No planning permit is required.

Additional permits that may be required, depending on the scope of work:

• An excavation permit for a new or upgraded utility connection or construction in the public right-of-way, such as the sidewalk, driveway approach.
• A fire permit for fire sprinklers.

Cost

Typical permit fees (includes inspections):

• For New Construction ADU:
  • building permit fees of $7,000 to $13,000, which is based on a construction valuation (cost of labor and materials) range of $100,000 to $300,000, and
  • if applicable, an excavation permit fee of up to $12,000, depending on the amount of utility improvements and construction in the public right-of-way.
• For Conversion of Existing Building Area into an ADU:
  • building permit fees of $3,000 to $5,000, which is based on a construction valuation range of $25,000 to $50,000, and
  • if applicable, an excavation permit fee of up to $12,000, depending on extent of utility improvements and construction in the public right-of-way.
• For a JADU: 
  • building permit fees of $4,000 to $6,000, which is based on a construction valuation of $25,000 to $35,000, and
  • if applicable, an excavation permit fee of up to $12,000, depending on extent of utility improvements and construction in the public right-of-way.
• Note: For building conversions into an ADU or JADU that involve the correction of a nonconforming zoning condition, building code violation, or unpermitted structure, no impact fees or connection/capacity fees will be charged unless new utility infrastructure is required to meet standards per Section 17920.3 of the Health and Safety Code.

The following fee is not collected or calculated by the City, but may be required for your project:

• School Impact Fees: All new residential square footage (new construction or conversion of existing square footage) greater than 500 square feet will be subject to School Impact Fees, which is due to the School District(s) prior to building permit issuance to start construction. The City requires proof of payment to the School Districts prior to issuing the building permit. 

Timeline

Typical Time to Receive Permit: 4 to 6 months

Process

1. City staff encourages you to review your preliminary ADU and/or JADU plans with the Planning Division prior to preparing detailed building plans. A Planner can confirm your project complies with minimum zoning requirements, which can streamline your building permit review. Contact the Planning Division at 650-903-6306 or planning.division@mountainview.gov.  
2. Submit for a building permit online. 
3. After your submission (during prescreen), City staff will contact you with the fee amount owed, based on your project scope, and instructions for online fee payment.
4. With confirmation of payment, City staff will review your permit application in 2 weeks and verify your application is complete and code compliant. If any information is determined to be incomplete or incorrect during the initial plan check, City staff will provide you comments and ask you to resubmit. 
5. You will need to reply to the city's comments with revised information or missing materials as part of your resubmittal online.
6. City Staff will review your resubmittal in 2 weeks to confirm you have addressed all of the City comments. If additional reviews and resubmittals are required, each additional cycle of review is 2 weeks for the City to give you comments. 
7. Additional permits may be required from the City for your project, including:
   
   1. A fire sprinkler permit to install a new, or modify an existing, fire sprinkler system in the ADU. This permit can be obtained after you receive your building permit, during the construction of your project.
   2. A demolition permit can be submitted at any time during your building permit but you must receive the demolition permit before you start construction or demolition activity.
   3. An excavation permit for any new or upgraded utility connection or for construction work in the public right-of-way. This permit must be obtained in tandem with obtaining your building permit.
8. Set up your account in the Construction and Demolition Waste Tracking system. If you have questions regarding Construction and Demolition Waste Tracking & Diversion Requirements, please contact Public Works at 650-903-6311 or public.works@mountainview.gov.
9. Once you have a complete and compliant permit, the city will issue you a building permit. This allows you to start construction of your project.
10. During construction, your contractor can schedule City inspections online at each stage of construction.
11. On-site inspections are completed by a City Building Inspector. If a Fire permit or Public Works permit is required for your project, inspections are conducted by each Department separately. The building permit is finaled and occupancy of the new ADU/JADU is granted upon completion of construction and a final inspection by the City Building Inspector.

Zoning Standards

Single-Family ADU Standards

Single-Family Junior ADU Standards

Multi-Family ADU Standards

Allowable exceptions to development standards to accommodate an ADU are available in City Code Section 36.12.95. 

Requirements

Building Plan Sheet Organization

The following information must be included in your building plans in the following order (see detailed submittal checklist):

• Cover sheet
• Blank sheet (page 0) titled "City Approvals"
• Dimensioned site plan
• Demolition plan
• Architectural plans
• Grading and drainage page
• Utility plan
• Construction plans and details
• Structural plans and details
• Structural calculations
• Electrical plans
• Electrical load calculations
• Mechanical plans
• Plumbing plans
• Landscape plans
• Equipment specifications
• Special conditions
• Include the Blueprint for a Clean Bay
• Title-24 energy calculations
• A completed Mountain View Green Building Code worksheet.