California ADU rules · Riverside County
Can I Build an ADU in Perris?
Yes — you can build an ADU in Perris. California's statewide ADU law requires every city, including Perris, 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 detached ADU OR 1 attached ADU + 1 JADU (max 2 total ADUs per lot, only one of attached/detached allowed in addition to JADU)
Cannot have both attached and detached ADU; only one plus a JADU.
Units on a multifamily lot
Local ruleConversions: at least 1 or up to 25% of existing units (rounded down, min 1); Detached: up to 8, but not more than number of existing units (up to 2 for proposed multifamily)
Detached ADUs capped at 8 or number of existing units, whichever is less.
Junior ADU (JADU)
Local ruleAllowed
JADUs allowed only on single-family lots, not on multifamily or where a portion of the primary dwelling is already an ADU.
Size & height
Max detached ADU size
Local rule1,200 sq ft
Studios/1-bedrooms: 850 sq ft; 2+ bedrooms: 1,200 sq ft or 75% of primary dwelling, whichever is less.
Max attached ADU size
Local rule50% of primary, not to exceed 850 sq ft (studio/1-bed) or 1,000 sq ft (2+ bed)
Local cap for attached ADUs is lower than state for 2+ bedrooms.
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
CA state law16 ft
16 ft baseline; cities must allow 18 ft within ½ mi of a major transit stop or where the primary dwelling is two-story, and 20 ft on a lot with a multistory multifamily building.
Setbacks
Side setback
Local rule4 ft
Minimum 4 ft or less if underlying zone allows; alley setbacks may be reduced with minor adjustment.
Rear setback
Local rule4 ft
Minimum 4 ft or less if underlying zone allows; alley setbacks may be reduced with minor adjustment.
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
No explicit minimum separation; underlying zoning may apply but cannot preclude an 800 sq ft ADU with 4 ft setbacks.
Parking
Parking required
Local ruleUp to 1 space
1 off-street space per ADU unless exempt; no parking required for converted (interior) ADUs or JADUs.
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/carport conversions.
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
Owner-occupancy required for JADUs only (deed restriction).
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.
Perris-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
ADU must have sprinklers if primary dwelling has them.
Perris allows either one attached or one detached ADU plus one JADU per single-family lot, but not both attached and detached ADUs together. Detached ADUs are capped at 1,200 sq ft (2+ bedrooms) or 850 sq ft (studio/1-bed), and attached ADUs have a lower local cap than state for 2+ bedrooms.
Frequently asked questions
Can I build an ADU in Perris?
Yes. California's statewide ADU law requires Perris 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 Perris?
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 Perris?
Side and rear setbacks are limited to 4 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 Perris?
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 Perris?
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 Perris?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Perris Municipal Code Chapter 19.81, as amended by Ord. No. 1449 (effective Feb 11, 2025)
- PMC §19.81.070(2), §19.81.080(2), §19.81.090(2), §19.81.100(2)
- PMC §19.81.110(2)
- PMC §19.81.100(4), §19.81.050(c)-(d)
- PMC §19.81.080(4)
- PMC §19.81.070(4)
- PMC §19.81.060(3), §19.81.080(5)
- PMC §19.81.060(9)
- PMC §19.81.120, §19.81.090(7), §19.81.100(8)
- PMC §19.81.120(a)(3), §19.81.090(7)(a)
- PMC §19.81.130(c)(1)(d)
- PMC §19.81.060(8)
- 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 § 66321 (size minimums & height)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- 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 2026-06-25. This is an AI-assisted summary of Perris'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 Perris Planning before relying on it.
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