Riverside County Additional Residential Accommodations ("ARA")
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Questions?
Please contact:
Riverside County Planning Department
(951) 955-3200 
ARA STANDARDS (ADUs, JUNIOR ADUs, SECOND UNITs AND GUEST QUARTER)*
 STANDARD  ADDITIONAL RESIDENTIAL ACCOMMODATION (ARA) TYPES
(Additional table coming soon with Ranchets and MOG Standards)
INTERIOR or ATTACHED DETACHED
ADU SECOND UNIT (SU) Guest Quarter (GQ)
ACCESSORY
DWELLING
UNIT (ADU)
Junior ADU
 
Single Family 1 unit/lot 1 unit/lot
Multifamily 1 interior unit/lot
(or a quantity that is
≤ 25% of existing
multifamily units,
whichever is greater)
N/A 2 units/lot N/A N/A
 
Kitchen Full Cooking appliance,
prep. counters, &
storage cabinets,
at a minimum
Full None allowed
Bathroom
(Minimum)
Toilet, shower, sink Toilet, shower, sink
(may shared
facilities with
house permitted)
Toilet, shower, sink Optional
 
Lot Size Permitted on
any lot size
> 7,200 s.f. Permitted on
any lot size
Lot Coverage Set by zoning classification (ADU floor area not included in the calculation)
Setbacks,
rear/side
(Minimum)
4 feet (for addition) 4 feet Per zoning
Floor Area
(Maximum)
≤ 50% of primary unit
floor area; no less than
800 square feet (sf)
(or 1,000sf,
whichever is less)
 ≤ 50% of primary
unit floor area
(or 500 sf,
whichever is less)
1,000 sf Max. floor area
depends on lot size:

- up to 1,200 s.f. unit
(7,201-20,000 s.f. lots);

- up to 1,500 s.f. unit
(20,000 s.f.-1.99 ac. lots)

- up to 2,500 s.f.
(2 ac.-3.99 ac. lots)

- up to 200% of
primary house area
(4+ ac. lots)

2% of lot size
(or 600 s.f,
whichever
is less)

Height N/A (only in one story) 16 feet No taller than
primary unit
Per zoning
Parking
(Replace-
ment parking
if existing
space(s) are
converted?)

Interior w/in existing struct./Junior ADU:
None required (no replacement)

Interior within new structure:
See detached ADU

1 space/unit
(no replacement)
- regular or
tandem spaces
- may be waived

1 space for
one-bedroom units; or
2 spaces for units
with two or more units
-regular or
tandem spaces
(replacement
may be ​required)

None
required
(no replacement)

 
Review

60 days from complete application, if primary unit exists
(Per Building Code, if primary unit is new)

Per Building Code
Occupancy


Owner does not need
to live onsite

Owner must
live onsite


Owner does not need
to live onsite

Owner must live onsite

*Draft standards: the above standards may be amended from time to time to correct errors or update interpretations. Last updated: 9.24.20
PDF version: Standards Matrix (under revision)