Accessory Dwelling Unit (ADU)
Background
An Accessory Dwelling Unit (ADU) is a smaller secondary dwelling unit to an existing primary dwelling unit. The County of Fresno encourages the development of ADUs by offering pre-approved plans at no cost to homeowners. The plans offer a variety of designs and sizes that will match the diversity of Fresno County and the needs of households throughout the county.
Additional Information
The County of Fresno Department of Public Works and Planning encourages housing development in the unincorporated area of Fresno County. The Department is offering County pre-approved plans for ADUs at no cost to homeowners interested in constructing a second unit on their property. If you live in an eligible County unincorporated area and you are interested in building an ADU, choose a design and size that fits your needs and contact our team to see if it can be built on your property.
Accessory Dwelling Units are currently not allowed within low water areas. You will need to contact our Zoning department to verify if your property is within one of these areas before you apply for an ADU.
For information on properties, zoning ordinance, and allowed uses, please contact our Zoning department at (559) 600-4540 or ZoningEnforcement2@fresnocountyca.gov.
ADU Plan Options
Plans are separated by options within an approximate size. Each size has 3 options available. Our department will provide a watermarked set for applications — once your application has been approved, we will provide you with the properly approved set for inspections.
Additional Considerations When Building an ADU
Fresno County is offering pre-approved ADU building plans but be advised that there are many additional items to consider beyond permit fees.
Even when several projects are built from the same plans, they will all be unique in a variety of ways: location, orientation (north, south, east, west facing), source of power supply, sewage disposal connection, general access and/or vehicle parking, etc.
Consultation with an industry professional is highly recommended. Complete scope of work and total project cost can be drastically impacted by requirements that may not have been considered.
Carefully consider the items below prior to undertaking a new ADU project.
Solar
Solar systems are a requirement for any new construction of residential property in the State of California. The size of the solar system required will be based on the size of the ADU to be built. The required size of solar is shown in kilowatts (Kw) and can be found on the front sheet or Title 24 section of the plan set.
A new solar system for the proposed ADU may not be required if the property has an existing solar system. The existing solar system must meet or exceed the State of California minimum requirements for both the primary residence and new ADU.
To calculate the required solar production, refer to 2022 California Energy Code Joint Appendix JA11 and Equation 150.1-C.
Fire Sprinklers
Fire sprinklers may or may not be required. If the primary residence currently has fire sprinklers, then the new ADU is also required to have them.
Fresno County Public Works and Planning has a policy of not requiring fire sprinklers on an ADU if the primary residence does not contain fire sprinklers. However, the local fire protection district should be consulted as they have the authority to implement all aspects of the 2022 California Fire Code.
Sewer/Septic
If the primary residence has a septic system, a new ADU will need a separate septic system installed.
If the primary residence is connected to a sewer system, the new ADU can be connected to the primary residence waste system between the existing house and sewer connection. The existing waste piping must be of sufficient size to accommodate the additional fixtures of the new ADU. A separate sewer tie in is also a possibility. Consult with the local utility provider for further information and costs.
Water Connection
Consider the method and location for connection of water supply to the new ADU. Contact your local service provider for further information if needed.
Trusses
Trusses are manufactured by several companies. As Fresno County will not recommend a certain manufacturer, it will be the responsibility of the property owner or contractor to choose a manufacturer and provide truss calculations to Fresno County Public Works and Planning for review and acceptance.
Electrical Power Supply
Review the required electrical power demand for the proposed ADU provided on the plans.
Interconnection with the main electrical panel at the primary residence is allowed. The existing main electrical panel must have the power capacity to support both the existing residence and the new ADU. The existing electrical panel can also be upgraded for higher capacity on a separate permit.
An independent power supply to the new ADU is also allowed. Consult the local utility provider for all requirements and costs regarding this option.
School Fees/RTMF
School fees may be required. Our office will provide a school fee form for all ADUs to be taken to the school district for determination if fees are applicable. Junior ADUs under 500 sq. ft. are not subject to school fees.
A Regional Transportation Mitigation Fee may be required by the Fresno Council of Governments. A form will be provided at permit issuance to take to their office to determine if they will require the fee to be paid.
** If an individual project may be exempt from a certain requirement, submit proof to Fresno County Public Works and Planning during the zoning review process for verification and acceptance.
Download a Copy of This Information as a PDF Here(PDF, 192KB)
Additional Documents Required
While the County will provide you with structural/electrical plans, we will still require a site plan and grading/drainage plan. Please see the below documents that detail what is required for both.
Plot Plan Example(PDF, 1MB)
Grading & Drainage Plan Submittal Requirements(PDF, 1MB)
Other plans/documents will be required depending on what is already existing on your property or what you will need to do on your specific site. These can include:
- Roof Trusses
- Fire Sprinklers
- Solar PV
- HVAC
- Septic System (separate permit)
Permit Costs
See below for the permit fees of each plan option.
500 Sq. Ft. Option 1
Total Fees: $2118.42
Building Plan Check - $257.00
Building Construction Permit - $792.25
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $6.92
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $3.00
500 Sq. Ft. Option 2
Total Fees: $1958.83
Building Plan Check - $255.00
Construction Permit - $784.75
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $6.83
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $3.00
500 Sq. Ft. Option 3
Total Fees: $2128.54
Building Plan Check - $259.50
Building Construction Permit - $799.75
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $7.04
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $3.00
749 Sq. Ft. Option 1
Total Fees: $2371.17
Building Plan Check - $318.00
Building Construction Permit - $979.75
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $10.17
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $4.00
749 Sq. Ft. Option 2
Total Fees: $2351.44
Building Plan Check - $313.50
Building Construction Permit - $964.75
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $9.94
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $4.00
749 Sq. Ft. Option 3
Total Fees: $2361.12
Building Plan Check - $315.50
Building Construction Permit - $972.75
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $10.12
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $4.00
1000 Sq. Ft. Option 1
Total Fees: $2654.65
Building Plan Check - $372.50
Building Construction Permit - $1147.25
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $13.15
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $5.00
1000 Sq. Ft. Option 2
Total Fees: $2678.68
Building Plan Check - $372.50
Building Construction Permit - $1147.25
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $13.18
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $5.00
1000 Sq. Ft. Option 3
Total Fees: $2504.68
Building Plan Check - $372.50
Building Construction Permit - $1147.25
Call-In, Fax, Email or Internet - $20.00
Microfilm/Copies - $99.75
Workers Comp. - $7.50
Mechanical Permit Issuance - $38.00
Mech. Install Dwellings Only - $46.00
Elec. Install Dwellings Only - $110.00
Electrical Permit Issuance - $38.00
Gas Appliance or Vent - $38.00
Plumbing Permit Issuance - $38.00
No of Bathrooms Dwellings - $179.00
On Site Sewer Piping - $ 89.00
Minimum Mechanical Permit fee - $61.00
Minimum Electrical Permit fee - $58.50
Minimum Plumbing Permit fee - $58.50
SMI - $13.18
On Site Water Piping - $89.00
On Site Gas Piping - $89.00
CA Bldg Standards Comm. Fee - $5.00
When you are ready to submit an application, please visit our Citizens Portal to submit all of your documents:
Citizens Portal