Accessory Dwelling Units (ADUs)

Benefits of Accessory Dwelling Units (ADUs)

What is an ADU?

What is a Junior ADU (JADU)?

Attributes of ADUs

Resources for Developing ADUs and JADUs

Pre-Approved ADU Plans

Town's Pre-Approved ADU Plans Inventory List (Updated July 8, 2025)
Zoning Code Requirements & Applications
ADU Survey
ADU Information Request List

Benefits of Accessory Dwelling Units (ADUs)

Accessory Dwelling Units (ADUs), commonly known as “granny units” or “in law units”, are encouraged by the Town of Woodside.  ADUs create valuable housing opportunities for aging parents, adult children, onsite workers and health care aids, and property owners seeking prospective rental units. 

What is an ADU?

An ADU is an attached or detached residential dwelling unit which provides complete independent living facilities for one or more persons; and includes a full kitchen and bathroom that provides permanent provisions for living, sleeping, and sanitation on the same parcel as the single-family dwelling. Manufactured/prefabricated/modular homes and tiny homes are allowed and would be subject to the same standards of custom build ADUs. 

What is a Junior ADU (JADU)?

A Junior ADU (JADU) is an ADU that is no more than 500 square feet in size, is contained entirely within an existing or proposed main dwelling, includes an efficiency kitchen, and has a separate exterior entry from the main dwelling. It must contain an interior connection to the main residence if it does not contain an independent full bathroom.

Attributes of ADUs

All ADUs in Woodside must have a permanent foundation and permanent utilities and are approved via a Building Permit only. ADUs can be attached to the main dwelling, detached, above a garage, in a basement (with proper egress), or the conversion of an existing accessory structure, such as a detached garage or barn. One parking space is required for ADUs with one or more bedrooms (unless a parking waiver applies in limited circumstances), and no parking is required for studio ADUs (no separate bedroom). ADUs can be up to 1,500 square feet.  ADUs can also be rented for no less than 30 days. 

Resources for Developing ADUs and JADUs

1. Meet with a Town Planner to learn about your property specific ADU development opportunities and the most up-to-date Woodside ADU Zoning Development Standards and State laws.
2. The Town is a member of the San Mateo County ADU Resource Center who provides information, resources, and tools to make it easier and less expensive for homeowners to build ADUs in San Mateo County. They offer:
   1. A free 1-hour personalized virtual feasibility consultation with an ADU specialist no matter what stage of development residents are at;
   2. Budgeting and finance estimations, which include a user-friendly ADU Budgeting Tool, understanding the types of financing available, and how an ADU may impact your property tax assessment and home value;
   3. The overall permitting process to help residents understand the design and construction process, including hiring your professional team and getting bids for construction contractors;
   4. Information regarding what is required to rent your ADU/JADU and manage the rental unit over time;
   5. Connections directly to State "Pre-Designed and Pre-Approved ADU Plans" for inspiration and potential use, and; (Note: Please contact the Planning Department to confirm if your desired ADU design would meet the Town’s Development Standards and Code Requirements prior to purchasing or using any designs. See more details below regarding Pre-Approved ADU Plans.)
   6. Educational ADU webinars and recordings of past webinars hosted by the ADU Resource Center, which are posted HERE.  

Pre-Approved ADU Plans

Previously approved Accessory Dwelling Unit (Pre-Approved ADU) plans are intended to provide a cost-effective and expedited review process for new construction of detached ADUs for property owners in Woodside. 

ADU vendors, such as architects and designers, will have the opportunity to submit architectural and structural drawings that are not site-specific to be reviewed by Town staff for preliminary code compliance. If approved, the Town will add the Pre-Approved ADU plans to the Town's Pre-Approved ADU Plans Inventory List allowing property owners to view for potential use in Woodside, subject to complying with all site-specific constraints, such as: geotechnical and seismic hazards, easements, steep slopes, stream corridors, septic and infrastructure suitability, Fire District standards, etc.

Vendors

The Town is currently accepting applications for pre-approved ADUs by vendors. Please contact the Planning Department to discuss the application process, submittal requirements, and fees. Once the plans are approved, the Vendor’s business name, contact information, a brief description of the size/type of approved detached ADU plan, and an ADU elevation and floor plan (subject to Vendor’s approval) will be listed on the Town’s Pre-Approved ADU Inventory List.

Note: Plans will need to be updated and resubmitted when the Town adopts new Building Codes, building policies, or Zoning changes that apply to the plans. Also, staff must remove listings from Town website within 30 days if requested by the designer.

Property Owners (Updated July 8, 2025)

San Mateo County ADU Resource Center’s Pre-Designed and Pre-Approved Plans for inspiration or potential use. Please be sure to contact the Planning Department prior to purchase or use of any designs to ensure the ADU complies with the Town’s development standards. 

Once it is confirmed by the Planning Department and other Town agencies that the Pre-Approved ADU design is suitable for the subject site, the property owner may submit the site-specific plans with applications for construction permits through the Building Department, the Fire District and County Health Department, if applicable. 

Projects that require modifications to the Master ADU Plan due to site-specific constraints will disqualify it as a Pre-Approved ADU and expedited review cannot be provided. It will be submitted through the standard building permit review process.

Town’s Pre-Approved ADU Plans Inventory List (Updated July 8, 2025)

No Pre-Approved ADU plans have been added to the Town’s Inventory List yet. Please check back at a later date!

Zoning Code Requirements & Applications

1. Zoning Code Requirements - Chapter 153.211 - Accessory Dwelling Units (Adopted April 8, 2025) [Note: Other development standard requirements are found in the Woodside Municipal Code, such as Chapters 151 (Site Development) and 153 (Zoning).]
2. Building Permit Application (PDF)
3. Building Submittal Checklist (PDF)
4. Planning Department Building Permit and Site Development Permit Submittal Requirements (PDF)
5. Site Development Permit Application(PDF)

ADU Survey

Please contact your project Planner for a link to the new online ADU survey. Contact information can be found in the Planning Staff Directory.