California ADU rules · Riverside County
Can I Build an ADU in Rancho Mirage?
Yes — you can build an ADU in Rancho Mirage. California's statewide ADU law requires every city, including Rancho Mirage, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
Local rule1 ADU + 1 JADU (JADU must be within primary dwelling)
JADU must be within the existing single-family residence.
Units on a multifamily lot
CA state lawConversion ADUs (≥1, up to 25% of units) + up to 8 detached
Conversions of non-livable space (at least 1, or up to 25% of existing units) plus up to 8 detached ADUs on a lot with existing multifamily — never exceeding the number of existing units. JADUs are single-family only.
Junior ADU (JADU)
Local ruleAllowed
One JADU allowed per single-family lot, must be within the primary dwelling.
Size & height
Max detached ADU size
CA state law1,200 sq ft
Statewide default cap for detached new-construction ADUs in the absence of a compliant local ADU ordinance. The unconditional by-right floor a city must always allow is 800 sq ft (see Guaranteed minimum size); a city with a compliant ordinance may set its own ceiling.
Max attached ADU size
Local rule50% of primary dwelling, up to 1,200 sq ft
State floor of 850/1,000 sq ft applies if 50% rule is less.
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule0 ft
Must conform to underlying zoning district height; no specific ADU height limit in local code. State floor of 16 ft applies.
Setbacks
Side setback
Local rule0 ft
Must meet zoning district setbacks unless state minimum (4 ft) applies for new construction.
Rear setback
Local rule0 ft
Must meet zoning district setbacks unless state minimum (4 ft) applies for new construction.
Front setback
CA state lawNo front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone
Separation from main house
Local ruleNone required
Must meet zoning district standards for distance between structures; no specific ADU separation.
Parking
Parking required
Local ruleUp to 1 space
Max one space per unit or per bedroom (whichever is less); exemptions per state law.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
Local ruleNot required
No replacement parking required for garage conversion if minimum parking for main dwelling is still met.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
Local ruleOnly for a JADU
No owner-occupancy for ADUs; JADUs require owner-occupancy in either JADU or main dwelling.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
CA state lawBuilding permit
Only a ministerial building permit — no conditional use permit or discretionary design review for a qualifying ADU.
Rancho Mirage-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire sprinklers not required for ADUs if not required for primary residence
Alternative fire protection allowed for ADUs; no additional sprinkler requirement.
Historic district parking exemption
No parking required for ADUs in historic districts.
Rancho Mirage limits detached ADU size to 30% of the primary dwelling if under 4,000 sq ft, or 1,200 sq ft if larger, but must allow at least 800 sq ft per state law. JADUs are allowed only within the primary dwelling and require owner-occupancy.
Frequently asked questions
Can I build an ADU in Rancho Mirage?
Yes. California's statewide ADU law requires Rancho Mirage to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Rancho Mirage?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Rancho Mirage?
Side and rear setbacks are limited to 0 ft. No front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone.
Is parking required for an ADU in Rancho Mirage?
Up to 1 space. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Rancho Mirage?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Rancho Mirage?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Rancho Mirage Municipal Code § 17.30.200 (ADUs), § 17.30.205 (JADUs); Ord. 1148 (2019)
- RMMC § 17.30.200(C)(2)(g), § 17.30.205(C)(1)
- RMMC § 17.30.205(C)(1)
- RMMC § 17.30.200(C)(2)(e)
- RMMC § 17.30.200(C)(2)(h)
- RMMC § 17.30.200(C)(4)
- RMMC § 17.30.200(C)(2)(k)
- RMMC § 17.30.205(C)(1)(b)
- RMMC § 17.30.200(C)(2)(j)
- RMMC § 17.30.200(C)(4)(b)(ii)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated Ord. 1148 (2019). This is an AI-assisted summary of Rancho Mirage's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Rancho Mirage Planning before relying on it.
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