To permit an ADU in Riverside, CA, you need a set of construction drawings that shows the city exactly what you plan to build. Riverside's building department reviews those drawings before issuing a permit, and the package has specific requirements. Without the right drawings, your application stalls before it begins.
This page covers what goes into a Riverside ADU permit drawing set, how long review takes, what it costs, and where to start if you don't yet have drawings.
Riverside ADU at a glance
1,200 sq ft
Max ADU size (detached)
6 weeks
Estimated plan check time
$4,217 to $6,817
Estimated permit fee range
4 ft
Rear and side setbacks
What goes into an ADU drawing set for Riverside
A permit drawing set is a collection of technical documents that tells the city, and later the builder, precisely how the unit is constructed. Riverside's building department checks drawings against the California Building Code, state ADU law, and the city's own zoning rules.
A complete ADU drawing set for Riverside typically includes:
Site plan. A bird's-eye view of the lot showing where the new ADU sits relative to the property lines, the main house, and any other structures. The site plan is how the city confirms your setbacks: detached ADUs in Riverside need at least 4 feet from the rear and side property lines. It also shows lot coverage and existing utilities.
Floor plan. A scaled drawing of each floor of the ADU showing room dimensions, door and window locations, and how the space is laid out. The floor plan establishes that the unit meets California's minimum habitable-space requirements (typically a 150-sq-ft main room for a studio, plus bathroom and kitchen) and Riverside's size cap of 1,200 sq ft for a detached unit.
Exterior elevations. Drawings of all four sides of the building showing roof line, window and door openings, exterior finish materials, and overall height. Riverside uses these to check that the ADU fits the neighborhood and, in historic districts, that it meets any design compatibility rules.
Foundation plan. Shows the type of foundation (slab, raised, or other) with dimensions and reinforcing specifications. California is seismically active, so the structural detail here gets real scrutiny.
Framing and structural plans. Wall sections, roof framing, beam and header schedules. For two-story ADUs (allowed up to Riverside's height limit), a structural engineer's stamp is typically required.
Electrical, mechanical, and plumbing plans (MEP). Shows panel location, circuit layout, HVAC, water supply, and drain lines. California requires a separate laundry area or hookup connection in any ADU, and Riverside checks that it's on the drawings.
Title 24 energy compliance report. California's energy code applies to all new ADUs. The compliance report shows insulation values, window-to-floor ratios, and HVAC efficiency. A code-compliant energy report is not optional.
Details and notes sheet. Waterproofing at shower and tub areas, window egress sizes, smoke and carbon monoxide detector locations. The building department flags missing details during plan check.
The city will not accept hand-drawn or approximate sketches. Drawings must be to scale (typically 1/4" = 1'-0" for floor plans), produced in a standard format, and signed by the designer or engineer of record.
Riverside ADU permit fees and plan check timeline
Once you submit drawings, Riverside's building department puts your application through plan check: a line-by-line review against the code.
Estimated plan check time: about 6 weeks. That's the typical figure for a standard ADU application in Riverside. Complex projects, or applications with errors in the drawing set, can take longer. Riverside offers an over-the-counter review for very simple projects, but most ADUs go through the standard queue.
Estimated permit fees: $4,217 to $6,817. That range covers building, electrical, mechanical, and plumbing permits for a typical detached ADU. The actual fee depends on the project's valuation, which Riverside calculates based on square footage and construction type. Impact fees (school and traffic fees) may be additional for detached units over a certain size threshold set by state law. Confirm the current fee schedule with Riverside's building department before budgeting.
Permit portal: applications go through Riverside's online portal at riversideca.gov/cedd.
If the plan checker finds issues, you get a correction letter. You revise the drawings and resubmit. A clean set on the first submission saves four to eight weeks of back-and-forth, which is why the drawing package matters so much upfront.
Riverside ADU rules that affect the drawings
The drawings have to reflect the rules, so it's worth knowing the key ones before your designer starts.
Size. Detached ADUs in Riverside can be up to 1,200 sq ft. Attached ADUs are limited to 50% of the main house's living area, up to 1,200 sq ft. Junior ADUs (JADUs), which are carved out of the existing house, cap at 500 sq ft.
Setbacks. 4 feet from the rear and side property lines for detached ADUs. Front setbacks follow the main house's setback. A 4-foot setback is the California state minimum that Riverside has adopted.
Height. Up to 2 stories for detached ADUs on most lots, subject to Riverside's specific height limit (typically 16 feet for a one-story, up to 25 feet for two-story, confirmed at permit intake).
Owner occupancy. Riverside does not currently require the property owner to live on-site to build or rent an ADU, consistent with California state law.
Historic districts. If your property is in one of Riverside's historic districts, the ADU requires additional design review. The drawings have to meet compatibility standards for materials, massing, and detail. This adds time and sometimes cost to the drawing process. Check the city's historic resource map before you start.
Short-term rentals. California allows cities to restrict ADU rentals to terms of 30 days or more. Riverside has its own short-term rental ordinance. If you plan to rent your ADU on a platform like Airbnb, confirm the current rules with the city before you build, because the business model affects whether the project makes financial sense.
For a full look at how Riverside's rules fit into the broader ADU picture in California, see our guide to ADU building permits and the What Is an ADU complete guide.
What it costs to build an ADU in Riverside
Construction drawings are only the first cost. Once permitted, you need a builder.
Estimated construction cost in Riverside runs $325 to $400 per sq ft for a new detached ADU (estimated, from our city data, last verified 2026-07-12). A 600-sq-ft one-bedroom ADU would cost an estimated $195,000 to $240,000 to build, not counting the drawings, permit fees, or any site work (utility connections, grading, etc.).
To put that cost in context: a one-bedroom ADU in Riverside rents for an estimated $1,645 per month, and a two-bedroom rents for an estimated $1,700 per month (estimated, from our city data). At those rent levels, a $200,000 ADU pays back in roughly 10 years from rental income alone, before accounting for property value gain.
Those are estimates, not guarantees. Actual rents depend on condition, location within the city, and the market at the time you rent.
For a broader cost breakdown, see ADU construction cost: real numbers by type, size, and state.
Does your Riverside lot qualify for an ADU?
We check your property against Riverside's current rules for free. Setbacks, size limits, historic overlays, utility connections. You pay nothing if your lot doesn't qualify.
Check my lot freeHow to get permit-ready drawings for your Riverside ADU
You have a few paths to a complete drawing set.
Hire a licensed architect or designer. An architect or licensed building designer (C-20 or equivalent) can produce a full permit set for a Riverside ADU. Expect to pay $8,000 to $20,000 or more depending on the designer's rate and the project complexity. Timeline from contract to permit-ready drawings is typically 6 to 12 weeks.
Use pre-approved ADU plans. Some jurisdictions have pre-approved plans that skip plan check for standard designs. Riverside does not have a formal pre-approved plan program at this writing, so your drawings go through standard plan check regardless of the design source.
Work with a full-service ADU company. A company that handles design, drawings, and permit management reduces the back-and-forth between you and the city. We handle the city. You make the decisions. That's what the Backyard Wealth Package is: we confirm your lot qualifies (free), produce permit-ready drawings, handle the city, and connect you to financing and a vetted builder. $6,000 flat, about what an architect charges just to start. And we guarantee your construction documents will be accepted for submission by your city, or we revise them free.
The starting point for any of these paths is the same: confirm your lot qualifies under Riverside's rules before you pay anyone to draw anything.
Frequently asked questions
What drawings does Riverside require to permit an ADU?
Riverside requires a full construction drawing set that includes a site plan, floor plan, exterior elevations, foundation plan, framing and structural plans, electrical, mechanical, and plumbing plans, a Title 24 energy compliance report, and a details and notes sheet. Drawings must be to scale and signed by the designer or engineer of record. The city checks every sheet against the California Building Code and Riverside's zoning rules during plan check.
How long does ADU plan check take in Riverside?
Estimated plan check time in Riverside is about 6 weeks for a standard ADU application. Applications with errors or missing information take longer because you must revise and resubmit. A clean, complete drawing set on first submission is the single biggest factor in keeping to that timeline.
How much are ADU permit fees in Riverside, CA?
Estimated permit fees in Riverside range from $4,217 to $6,817 for a typical detached ADU, covering building, electrical, mechanical, and plumbing permits. The actual fee depends on the project's assessed valuation. School impact fees and other development fees may apply separately. Confirm the current fee schedule with Riverside's Community and Economic Development Department.
Can I build a two-story ADU in Riverside?
Yes. Riverside allows two-story detached ADUs on most lots, subject to the city's height limits. A two-story design typically requires a structural engineer's stamp on the framing plans. If your property is in a historic district, the design may need to meet additional compatibility standards before the city will approve a two-story structure.
Do I need an architect for an ADU in Riverside?
California law does not require a licensed architect for ADU drawings (a licensed building designer or qualified engineer can also prepare them), but Riverside's building department requires drawings that are produced to code, to scale, and signed by the designer of record. Unlicensed sketches are not accepted. Whether you hire an architect, a designer, or a full-service ADU company, the drawings have to meet the same technical standard.
Related reading:
