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Adding an Accessory Dwelling Unit (ADU) to your Riverside County property is a smart investment—but before construction begins, it’s essential to understand the permitting process. While it may seem complex at first, navigating ADU permits is much more straightforward when you know what to expect—and when you have the right team guiding you through every step.
At Honeywill Construction, we bring over two decades of experience and a deep understanding of local ordinances. Below is a clear, step-by-step breakdown of what’s required to legally permit your ADU, whether you’re building a detached backyard cottage, converting your garage, or adding a Junior ADU.
Step 1: Confirm Your Property’s Eligibility
Before any paperwork is filed, it’s critical to confirm that your property meets zoning and location requirements. Riverside County generally allows ADUs on most single-family residential lots, but you must check for:
- Zoning designation (R-1, R-A, RR, RE, etc.)
- Environmental restrictions (flood zones, historical overlays, cultural resource areas)
- Whether you have an existing or proposed primary dwelling
Honeywill Pro Tip: Use the County’s “Map My County” tool or contact Planning to check setbacks, flood status, and zoning.
Step 2: Choose Your ADU Type and Design
Select your ADU style—detached, attached, internal, garage conversion, or JADU—and determine if you’ll use:
- Pre-approved ADU plans (available from Riverside County and some cities)
- Custom ADU designs prepared by a licensed architect or draftsperson
Each option has different timeline and budget implications. At Honeywill, we can help you evaluate both.
Step 3: Prepare Required Documents
Once your design is finalized, you’ll need a set of permit-ready documents, including:
- Site plan with setbacks, ADU placement, and utility connections
- Floor plan, roof plan, and elevations
- Electrical, plumbing, and mechanical layouts
- Title 24 energy compliance report
- Structural calculations (especially for above-garage units)
- CALGreen construction waste form
- Hold Harmless Agreement (required in most jurisdictions)
Step 4: Submit Your Application Online
Most Riverside County ADU applications are submitted through the Public Permit Portal (PLUS Online). You’ll need to upload all required documentation and pay the initial application fees.
For those using pre-approved ADU plans, the plan check process is significantly faster—sometimes as little as 3–5 business days.
Step 5: Plan Review & Corrections
Once submitted, your plans will be reviewed by multiple departments:
- Building & Safety
- Planning Division
- Environmental Health (if septic)
- Fire Department (for access and sprinkler reviews)
Expect to receive correction notices for minor adjustments. These must be resolved before final approval. Honeywill’s team stays on top of all review timelines to ensure nothing falls through the cracks.
Step 6: Permit Issuance
After all plan reviews are approved and outstanding fees are paid, your ADU permit will be issued. You’ll receive a stamped digital copy of the approved plans, which must be printed and kept onsite throughout construction.
Step 7: Begin Construction & Schedule Inspections
Once permitted, construction can begin. Key inspection milestones include:
- Footing/Foundation: Before pouring concrete or setting piers
- Framing & Rough-In: After framing, plumbing, electrical, and HVAC are installed
- Insulation: Before drywall goes up
- Drywall & Final Inspection: Verifying finish work, code compliance, and safe occupancy
Inspection requests can often be made through the portal and scheduled for the next business day if submitted before 4:00 p.m.
Step 8: Certificate of Occupancy
Once your final inspection is passed, the city or county will issue a Certificate of Occupancy—officially allowing you to rent, reside in, or use the ADU.
Let Honeywill Handle the Permitting for You
Permitting can be the most technical and time-consuming part of an ADU project, but it doesn’t have to be overwhelming. At Honeywill Construction, we handle it all:
- Pre-application consultations
- Plan selection and design
- Permit submittal and corrections
- Communication with local departments
- Scheduling and passing all inspections
We’ve successfully navigated the process in cities across Riverside County including Temecula, Hemet, Moreno Valley, and Palm Springs. With our trusted team at your side, your ADU permitting journey will be smooth, timely, and fully compliant.
Ready to start your ADU project?
Call 951-294-0194 or send us a message to schedule a free consultation.
Want to explore layout ideas first?
Check out our Smart ADU Layout Ideas for Riverside County Homes to get inspired.
Helpful Resources for Your ADU Permits:
ADU Permiting FAQ
You’ll need a building permit from Riverside County, and depending on your project, you may also require planning clearance, grading, electrical, plumbing, and mechanical permits. If you’re converting a garage or building in a special zone, additional approvals may apply.
You can apply for an ADU permit by submitting your construction plans, required forms, and application through the Riverside County PLUS Online Permit Portal. Honeywill Construction can handle this process for you, from document prep to final submittal.
Your permit application must include site plans, architectural drawings, Title 24 energy compliance reports, a Hold Harmless Agreement, and the Permit-Ready Clearance Form. For detached units or garage conversions, structural calculations may also be needed.
If you’re using pre-approved plans, the initial review may take just 3 business days. Standard custom designs typically require 10–20 business days for first review, with revisions extending the timeline.
Permit fees in Riverside County can range from $3,000 to $9,000, depending on the size and scope of your ADU. Additional fees may apply for utility connections and impact assessments.
Yes, Riverside County offers a digital submittal system called the PLUS Online Permit Portal. You’ll need to create an account and upload all required plans and documents electronically.
The PLUS (Planning Land Use System) Portal is Riverside County’s online platform for submitting, tracking, and managing permit applications. It streamlines the ADU permitting process and keeps homeowners informed throughout.
Yes, Riverside County requires code-compliant architectural drawings prepared by a licensed professional. These include site plans, floor plans, elevations, electrical, plumbing, mechanical, and structural details.
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Standard setbacks for ADUs are 4 feet from the rear and side property lines. Front yard setbacks follow existing zoning rules. Conversions may be exempt if dimensions aren’t changed.
Yes, separate trade permits for plumbing, electrical, and mechanical work are required and must be submitted alongside or after your main building permit.
