Pre-Approved ADUs
The Pre-Approved ADU Program will make plans for different ADU types, styles and sizes available to the public. Under this program, plans are designed by ADU builders, private licensed architects/engineers, and designers to accommodate various site conditions. Plans are then reviewed and pre-approved by the County of Santa Clara – Department of Planning and Development.
County Pre-Approved ADU Plans
The Department of Planning and Development offers the following pre-approved ADU plans to residents of unincorporated Santa Clara County free of charge and for public use:
- 800 sq. ft, 2-bedroom, 1 bath floor plan, in either Standard (Traditional) or Contemporary Architectural style
- 1,200 sq. ft, 3 bedroom, 2 bath floor plan, in either Standard (Traditional) or Contemporary Architectural style
When the applicant selects one of the pre-approved construction plans provided above and submits a project-specific site plan, energy calculations (Title 24 CF-1R forms), and a roof truss design from a truss manufacturer, county staff will review site-specific factors for your property, including compliance with the County Zoning Ordinance and California Energy Code requirements. Compliance with the current building code has been reviewed and pre-approved; therefore, these plans will provide a lower cost option for applicants and will reduce overall permitting time. Minimum plan review fees (2 hours) will be charged for applications using the pre-approved plans without modification. If the pre-approved plans have been modified using the available CAD files, the plans will need to be stamped and signed by licensed design professional, as applicable. Additionally, the modified plans will not qualify for the Pre-Approved ADU Program expedited review process. Plan review fees of this type of projects will be determined based on the project valuation.
Expedited permitting is not available to properties located in the Wildland Urban Interface, special flood hazard, or geologic hazard zones. Use the County Online Property Profile application to find out if your property is in one of these areas.
ADU Cost Calculator
Baird+Driscoll Community Planning with the Chan Zuckerberg Initiative, a non-government entity, has developed an ADU Cost Estimate Calculator for County residents to obtain an estimate of costs and return on investment for ADU building projects. This calculator can be accessed here: https://santaclaracounty.aduaccelerator.org/calculator
DISCLAIMER: The calculator provides a rough estimate on costs and financing. The County bases their building permit fees as a percentage of the cost of construction (valuation) provided by the applicant.
Pre-Approved ADU List
You can find a list of ADU builders and/or design professionals who have secured pre-approved plans below. These plans may be of prefabricated or conventionally built construction. A site-specific plan that shows the location of the pre-approved ADU is still needed for submittal. ADU builder/contractor would usually submit the site-specific plan; please consult with your ADU builder/contractor.
Listed in alphabetical order, the following vendors offer ADU plans that the County of Santa Clara has been pre-approved:
1. Prepare plans
Create ADU plans that are not site-specific and include the following:
- Architectural information, plans, elevations, sections, and details
- Structural information, plans, elevations, sections, and details
- Structural calculations
- Title 24 energy calculations
- CalGreen Checklist
- Truss plans and calculations, as applicable
- Indication of Fire sprinklers: Provide a statement as to whether the standard construction plan layout proposes to be equipped with an automatic fire sprinkler system.
- For ADUs, you may use code minimum soil valuation for foundation design, or pre-scripted footing sizes if conventional construction is used or match existing foundation.
- A standard site plan as reference is optional.
IMPORTANT: You will need to update and resubmit your plans when the County adopts new building codes, building policies, or zoning changes that apply to the plans.
2. Submit plans and pay fees
- Submit for permits, check status, and pay fees via the County Public Permit Portal.
- Submit an application through the County Public Permit Portal. If you have questions about the application submittal process, schedule an appointment and one of our staff will assist you. You can contact us at [email protected] or (408) 299-5700.
- See the Digital Submittal Requirements and Naming Conventions document for more information.
3. Plan review time
The plan review will take approximately 4 weeks for the first submittal and 2 weeks for subsequent submittals. These estimates are based on submitting complete and accurate plans.
4. Fees
Visit our Fees webpage and view the Building Section Fee schedule.
5. Get a listing on this webpage
Upon approval of the plans, your business name, contact, information, and brief description of the size/type of pre-approved ADU plan will be listed on this webpage.
I want to use pre-approved ADU plans. How do I proceed?
You can select a pre-approved ADU plan listed above and then work with the County (if using the County provided plans) or directly with vendors to purchase and submit the plans for County review and permitting. You may wish to contact several vendors and learn about their options, pricing, and installation approach. Be sure to confirm the vendor's role in submitting the plans and securing the building permit. It is highly advised that you have a California licensed contractor pull the permits. This keeps the liability for the work with the professional service.
Do I need an architect if I use a pre-approved plan?
While you are not required to have an architect design and stamp your ADU plans, you will need to have a designer produce the site plan, Title 24 calculations, and Solar PV plans (if required). A California licensed engineer from a truss manufacturer will need to stamp and sign truss drawings. If you are using the County provided pre-approved ADU plans, the truss design and calculations may be a deferred submittal.
What are the requirements to use the pre-approved ADU plans?
To use pre-approved plans, the project must at least meet all the following criteria:
- Lot must be in unincorporated Santa Clara County, zoned residential, and have a legally established single-family home or two-family dwelling (duplex).
- Lot must NOT be in the Wildland Urban Interface, a flood zone, or in a geologic hazard zone
- The project must NOT be in a historic property.
- The project address must NOT have an open Code Enforcement violation.
Please refer to ADU FAQ to see if your property is qualified for using this program.
Can I make changes to the pre-approved plans?
Changes to vendor provided pre-approved plans will not be permitted. However, room for customization is limited with the County pre-approved plans. You can change windows and door types, sizes and colors, and rotate floor plans. Minimal changes will allow you to maintain the pre-approved status, but larger changes to the floor plan are usually not permitted. Making changes to a pre-approved plan may disqualify it as a Pre-Approved ADU and expedited review cannot be provided.