The Pre-Approved ADU Program offers homeowners an efficient, straightforward path to adding ADUs by selecting pre-approved designs:

1. Pre-approving designs submitted by architects.
2. Making pre-approved plans available for quick selection.
3. Ensuring a streamlined site plan review process.

By choosing a pre-approved ADU plan, applicants benefit from a faster review process, reducing time and cost.

1. Architect/Designer Submit ADU Plans for Pre-Approval

• Design: Architects create plans that meet California and City requirements.
• Submission: Plans are submitted for an ADU Plan Check electronically through TESSA.
• Review: The Planning, Building, Public Works, Fire Departments, and outside agencies review plans for code compliance.
• Triennial Building Code Cycle: Pre-approved ADU plans must meet updated standards per California Building Codes. Architects must resubmit plans for re-approval following triennial code updates. Pursuant to AB 130, the next opportunity for substantive residential code changes is expected with the 2031 Code Cycle, which would go into effect on January 1, 2032.

2. City Review and Approval

• Planning Review: Ensures zoning code compliance.
• Building/Fire Review: Confirms structural, fire safety, and aging in place design (section R327 of the CRC).
• Final Pre-Approval: Approved plans are added to the City’s database, complete with vendor contact information.

3. Resident Selects a Pre-Approved Plan

• Browse: Applicants choose from the list of pre-approved ADU plans and contacts vendor.
• Prepare and Submit Site Plan: Vendor/Resident submit a Pre-Approved ADU Plan Check through TESSA showing details outlined in the Site Plan Review Checklist below. 

4. Site Plan Review and Final Approval

• Planning and Safety Review: Site plans are reviewed for zoning and safety compliance.
• Final Approval: Approved site plans receive a building permit, allowing construction to proceed.

5. Construction and Inspection

• Start Construction: Construction begins as per the approved ADU and site plans.
• Inspections: Required inspections occur throughout construction, ending with a final inspection.

COMING SOON! 

The City is currently working with interested architects to review proposed pre-approved ADU plans. Please check back in early 2025 when the City anticipates having Costa Mesa-approved ADU plans available.

Browse our directory to find Costa Mesa pre-approved ADU plans and vendor contact information. Each approved plan meets state and local regulations, ensuring compliance and faster project timelines.

Having these items on the site plan ensures a smooth review and speeds up the approval process for constructing the ADU.

1. Property Information

• Property address and Assessor’s Parcel Number (APN)
• North arrow and scale of the drawing
• Lot dimensions and total lot size
• Owner and applicant contact information
• Existing floor plan of main residence

2. ADU Location and Dimensions

• Proposed ADU location on the property, clearly marked and dimensioned
• Setbacks from property lines, main dwelling, and other structures
• Dimensions of the ADU (length, width, height)
• Distance from ADU to adjacent structures, including the main residence

3. Access and Parking

• Location of existing and proposed driveways, parking spaces, and access paths

4. Utilities and Infrastructure

• Location of existing and proposed utility connections (water, sewer, gas, electricity)
• Stormwater management or drainage plan, if required
• Grading details, especially if the site has significant elevation changes

5. Landscaping

• Landscaping around the ADU (e.g., plants, privacy hedges, hardscape, or fences)

6. Building and Safety Requirements

• Fire safety measures, including distance from other structures
• Fire hose pull distance (if greater than 150 feet, fire sprinklers are required)
• Compliance with building and safety codes (e.g., structural, fire access)
• Location of any nearby hazardous areas (e.g., steep slopes, flood zones)

7. Additional Required Documents/Permits

• Soils report (if the ADU is greater than 800 square feet)
• Solar (deferred submittal)

• Energy Title-24 Report

• Address change (initiated by the Planning Division)
• Sewer Permit – Submit to Costa Mesa Sanitary District
• Permit Requirements
• CCTV Requirements
• Sample Sewer Plan
• Water Improvement Plan – Submit to Mesa Water/Irvine Water District
• New service may be required if water lateral is shared with neighboring property.