Rancho Cucamonga allows one ADU plus one JADU on any lot with a single-family home, and conversion ADUs plus detached ADUs on multifamily lots, under Chapter 17.100 of the Municipal Code. A detached ADU can be up to 1,200 sq ft (attached: 50% of the house or 1,200 sq ft, whichever is less) with 4 ft side and rear setbacks and a 16 ft height limit (18 ft near transit). Permits are filed online only; Building & Safety's first plan review takes 10 business days, and the FY2026-27 ADU building-permit fee starts at $1,822 (up to 500 sq ft) plus 12% technology and 10% General Plan fees. No owner-occupancy is required for an ADU, city impact fees are waived for units of 750 sq ft or less, and rentals shorter than 30 days are not allowed.
Zoning & Size Requirements [1][2][3]
Yes — Rancho Cucamonga allows ADUs. A detached ADU can typically be up to 1,200 sq ft under current California and Rancho Cucamonga zoning rules.
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| Allowed Zones | Any lot zoned for residential use with an existing or proposed single-family or multifamily dwelling (RCMC Chapter 17.100; Gov. Code 66314). The city's ADU Handbook (May 2024) states ADUs are allowed on any parcel with a single-family home; multifamily lots may add conversion and detached ADUs. Hillside, septic and Wildland-Urban Interface Fire Area lots are eligible but carry extra review (OWTS approval; defensible-space landscaping plan). |
| Max Size (Detached) | 1,200 sq ft maximum, 350 sq ft minimum (Handbook p. 7; RCMC 17.100.050). Lot-coverage limits may cap a detached unit, but never below 800 sq ft at 16 ft height with 4 ft side and rear setbacks (Gov. Code 66321). |
| Max Size (Attached) | 50% of the main dwelling's floor area or 1,200 sq ft, whichever is less; 220 sq ft minimum (Handbook p. 8; RCMC 17.100.050). State law guarantees at least 800 sq ft regardless of the 50% rule (Gov. Code 66321). |
| Max Size (JADU) | 500 sq ft maximum, 220 sq ft minimum, entirely within the existing or proposed single-family house (an attached garage counts); the floor area of a shared bathroom is not counted (Handbook p. 10; RCMC 17.100.050(D)). One JADU per single-family lot; not allowed inside a detached ADU; a JADU sharing a bathroom needs an interior door to the main house. |
| Max Height | Detached: 16 ft; 18 ft within 1/2 mile walking distance of a transit stop or on a lot with a multi-story multifamily dwelling, plus up to 2 ft (20 ft) to match the main house's roof pitch (Handbook p. 7; RCMC 17.100.050(G)). Attached: the primary structure's height or 16 ft, whichever is higher; an ADU built over a garage follows the base-zone height limit (17.100.050(G)(2)). State law also allows an attached ADU up to 25 ft or the zone limit, whichever is lower (Gov. Code 66321). |
| Max Units | Single-family lot: one ADU (attached, detached or converted) plus one JADU (Handbook pp. 11, 19). Multifamily lot: conversion ADUs in non-livable space (at least one, up to 25% of existing units) plus up to two detached ADUs per the Handbook; state law since Jan 1, 2025 (SB 1211) allows up to eight detached ADUs on an existing multifamily lot, not exceeding the number of existing units. |
Setback Requirements [1][2][3]
Rancho Cucamonga requires a rear setback of about 4 ft for a detached ADU, and parking requirements vary by unit size or location. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 4 ft minimum from the rear lot line for new construction, detached or attached; converting an existing garage or accessory structure keeps its existing setbacks (Handbook pp. 7-9; RCMC 17.100.050). |
| Side Setback | 4 ft minimum from side lot lines for new construction; conversions keep existing setbacks (Handbook pp. 7-9; RCMC 17.100.050). |
| Front Setback | Base-zone front setback applies. An ADU may be placed in the front yard only when the rear yard cannot fit an 800 sq ft unit with 4 ft side and rear setbacks (Handbook FAQ p. 19). Driveways and walkways may cover no more than 50% of the front yard (RCMC 17.56.070). |
| Parking Required | 1 space (covered or uncovered) for a new detached ADU unless exempt: within 1/2 mile walking distance of public transit, in a historic district, converted from the existing house or an accessory structure, on-street permits required but not offered to the ADU occupant, car-share within one block, or a JADU (RCMC 17.100.050(J)(4); Handbook p. 12). Attached ADUs and garage or carport conversions need no parking (Handbook pp. 8-9); state law bars replacement parking for a converted garage. |
| Owner Occupancy | Not required for an ADU (Handbook FAQ p. 19). The Handbook (May 2024) says owner-occupancy is required for a JADU; since Jan 1, 2026 (AB 1154) a city may require it only when the JADU shares a bathroom with the main house, so a JADU with its own bathroom is exempt. |
| Min Lot Size | None. The Handbook sets no minimum lot size, and state law bars any lot-size, lot-coverage or floor-area rule that would prevent an 800 sq ft ADU (Gov. Code 66321). |
Permit Process & Fees [4][5][6][7][8]
An ADU permit in Rancho Cucamonga goes through a standard permit review. Typical timeline: First plan review within 10 business days (Building & Safety, Planning and Engineering concurrently); rechecks within 5 business days (Building & Safety page). State law deems an ADU approved if the city does not act within 60 days of a complete application (Gov. Code 66317; SB 543 from Jan 2026). Permit fees: FY2026-27 Master Fee Schedule (eff. July 1, 2026): ADU building permit $1,822 up to 500 sq ft plus $44 per additional 100 sq ft (about $1,954 at 800 sq ft, $2,130 at 1,200 sq ft), plus 12% technology and 10% General Plan fees and a $343 processing fee; $1,363 with a pre-approved plan.
| Approval Process | Everything is filed through the city's Online Permit Center (no counter permits). An ADU is a building-permit project; depending on type, size and height the Planning Division may first need to issue a plan check/zoning clearance (RCMC 17.100.040(A)). Building & Safety, Planning, Engineering and the Fire District review the same set, and the Handbook says to expect at least two rounds of comments (p. 15). Submittal list: Residential Building Plan Check Submittal Guidelines BSF-0002 (rev. Feb 11, 2026). |
| Review Timeline | First plan review within 10 business days (Building & Safety, Planning and Engineering concurrently); rechecks within 5 business days (Building & Safety page). State law deems an ADU approved if the city does not act within 60 days of a complete application (Gov. Code 66317; SB 543 from Jan 2026). |
| Permit Fees | FY2026-27 Master Fee Schedule (eff. July 1, 2026): ADU building permit $1,822 up to 500 sq ft plus $44 per additional 100 sq ft (about $1,954 at 800 sq ft, $2,130 at 1,200 sq ft), plus 12% technology and 10% General Plan fees and a $343 processing fee; $1,363 with a pre-approved plan. |
| Impact Fees | None for an ADU of 750 sq ft or less of interior livable space (Gov. Code 66311.5); larger units pay in proportion to the main house. City impact fees (FY2026-27) are charged per sq ft of single-family floor area: transportation $4.15-$6.03 by zone, plus library $0.43, animal center $0.09, police $0.15, park land $1.07, park improvement $1.99, community center $0.87 and fire district $0.37, about $9.10-$11.00 per sq ft before proration. School district and water district (CVWD) fees are billed separately. |
| Plan Check | 10 business days for the first review and 5 business days for each recheck (Building & Safety page, Sept 2026); the city notes processing times vary with scope of work. |
| Pre-Approved Plans | Program exists on paper: the city's AB 1332 page describes plan pre-approval and the FY2026-27 fee schedule sets a $1,363 permit fee for a 'Pre-Approved ADU Plan' up to 1,200 sq ft, but no pre-approved plans are posted on the city website as of Sept 2026. Ask Building & Safety (EDRnotification@CityofRC.us) whether any plan has been pre-approved; AB 1332 requires a 30-day decision on a detached ADU that uses one. |
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Construction Costs [9][10][11]
Building an ADU in Rancho Cucamonga typically costs $175,000-$350,000 ($250-$350 per sq ft); a garage conversion runs $75,000-$150,000.
See what this means for your lot — ask Rancho Cucamonga ADU builders for a quote →
| Average Build Cost | $175,000-$350,000 |
| Cost per Sq Ft | $250-$350 |
| Garage Conversion | $75,000-$150,000 |
| Prefab ADU (Installed) | $175,000-$350,000 |
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Rental Income Potential [12][13][14]
A 2-bedroom ADU in Rancho Cucamonga rents for around $2,600-$2,750/mo, an estimated 9-11% gross rental yield on a $250,000 detached 1BR at $2,150-$2,300/mo (about a 9-11 year simple payback), higher for a garage conversion; before taxes, vacancy and financing.
| Avg Rent (1 Bedroom) | $2,150-$2,300/mo |
| Avg Rent (2 Bedroom) | $2,600-$2,750/mo |
| Short-Term Rental | No. ADUs and JADUs must be rented for periods longer than 30 days (Handbook pp. 17, 19), and an ADU cannot be sold separately from the main house because the city has not adopted an AB 1033 ordinance (Handbook FAQ p. |
| Est. Annual ROI | 9-11% gross rental yield on a $250,000 detached 1BR at $2,150-$2,300/mo (about a 9-11 year simple payback), higher for a garage conversion; before taxes, vacancy and financing |
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Recent Law Changes
What's Changed Recently
- Sept 2026 re-verification: zoning fields rebuilt from the city's ADU Handbook (May 2024, RCMC Chapter 17.100) and fees from the FY2026-27 Master Fee Schedule (effective July 1, 2026); the unsourced claims that no planning approval is ever needed, that the city provides standard ADU designs and that R-1/R-2/R-3 are the eligible zones were removed
- Late 2025: the city processed an ADU/JADU code amendment (DRC2025-00072; Planning Commission hearing Oct 22, 2025) to fold the 2024 state laws (AB 2533, SB 1211) into Chapter 17.100; the amended text on eCode360 could not be read for this update, so confirm current section numbers with Planning
- Ordinance 1048 adopted the 2025 California Building, Residential and related codes (the state cycle effective Jan 1, 2026), which apply to ADU plans submitted from that date
- SB 543 (Jan 2026): ADU applications deemed approved if city fails to act within 60 days
- AB 1154 (effective Jan 1, 2026): A locality may require owner-occupancy for a JADU only if it shares a bathroom with the primary dwelling; JADUs with their own bathroom are exempt (matching detached ADU rules)
- FY2026-27 Master Fee Schedule (July 1, 2026) carries a dedicated ADU building-permit row ($1,822 up to 500 sq ft) and a $1,363 permit fee for pre-approved ADU plans
Tips for Building an ADU in Rancho Cucamonga
- Cost basis: build and garage-conversion ranges are Inland Empire figures from CaliFirst Remodel (May 28, 2026) and Construction Station (fetched Sept 2026); no separate prefab pricing was found for the Inland Empire, so the prefab figure is the detached-unit range - get installed quotes that include foundation, utilities and crane. Rents are Rancho Cucamonga medians from Zumper (Sept 19, 2026) and RentCafe (Aug 31, 2026).
- Worked fee example: an 800 sq ft detached ADU pays about $1,954 base permit plus 22% technology and General Plan fees plus $343 processing, roughly $2,730 to the city, plus school district and CVWD water/sewer charges; keeping the unit at 750 sq ft or less avoids city impact fees entirely
- New detached ADUs must have solar under Title 24 (Handbook p. 13); attached, conversion and prefab units are exempt. Lots in the Wildland-Urban Interface Fire Area on the north side of the city need a defensible-space landscaping plan
- Septic lots: get Building & Safety's OWTS approval before paying for final plans, and a lot within 300 ft of an existing sewer must connect to it (Handbook p. 13)
- Fire sprinklers are not required in the ADU if the main house does not have them, and the ADU may be separately metered for gas, electricity, water and sewer (Handbook p. 12)
- You can build in the front yard only when the backyard cannot fit an 800 sq ft unit with 4 ft setbacks (Handbook FAQ p. 19)
- Contacts: Planning@CityofRC.us or 909-774-4330 for zoning questions; EDRnotification@CityofRC.us or text 909-488-4668 for permits; inspections 909-477-2710 (Handbook p. 16; Building & Safety page)
- Studio rents run about $1,770-$2,000/mo (RentCafe Aug 2026, Zumper Sept 2026), so a garage-conversion studio can gross more per dollar spent than a detached 1BR build
- Cost basis (2026-09-20 re-verification): short term allowed: No. ADUs and JADUs must be rented for periods longer than 30 days (Handbook pp. 17, 19), and an ADU cannot be sold separately from the main house because the city has not adopted an AB 1033 ordinance (Handbook FAQ p. 19).
ADU Builders in Rancho Cucamonga
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- City of Rancho Cucamonga Accessory Dwelling Unit Handbook (updated May 21, 2024) - sizes, heights, setbacks, parking, number of units, FAQ | Planning Division Planning Department — Accessed 2026-09-20
- Accessory Dwelling Units news page (May 22, 2024) linking the current Handbook | City of Rancho Cucamonga Planning Department — Accessed 2026-09-20
- RCMC Title 17 Development Code, Chapter 17.100 ADUs and JADUs (eCode360; bot-walled, not readable this update) Municipal Code — Accessed 2026-09-20
- FY 2026-27 Master Fee Schedule, effective July 1, 2026 - Building & Safety R3 Accessory Dwelling Unit and Pre-Approved ADU Plan rows (p. 22), processing fees (p. 15), Development Impact Fees (pp. 11-14) | City of Rancho Cucamonga Planning Department — Accessed 2026-09-20
- Building & Safety Department - online-only permitting, 10 business day first review, 5 business day rechecks | City of Rancho Cucamonga Planning Department — Accessed 2026-09-20
- Assembly Bill 1332 (pre-approved ADU plan program) page | City of Rancho Cucamonga Building & Safety Planning Department — Accessed 2026-09-20
- BSF-0002 Residential Building Plan Check Submittal Guidelines (rev. C, Feb 11, 2026) | City of Rancho Cucamonga Building & Safety Planning Department — Accessed 2026-09-20
- Ordinance No. 1048 adopting the 2025 California Building Code cycle (City Clerk copy filed on eCode360; read via Wayback capture of Mar 7, 2026) Municipal Code — Accessed 2026-09-20
- ADU Costs in California (2026): City-by-City Numbers - Inland Empire section (May 28, 2026) | CaliFirst Remodel industry — Accessed 2026-09-20
- ADU Contractors Inland Empire - garage conversion, JADU and detached cost ranges | Construction Station industry — Accessed 2026-09-20
- ADU Cost in Los Angeles (2026) - Southern California per-square-foot range (updated July 28, 2026) | GreatBuildz industry — Accessed 2026-09-20
- Rancho Cucamonga, CA rent report (updated Sept 19, 2026) | Zumper industry — Accessed 2026-09-20
- Average rent in Rancho Cucamonga, CA (as of Aug 31, 2026) | RentCafe industry — Accessed 2026-09-20
- ADU Handbook (May 2024) - Renting My ADU and FAQ: no rentals under 30 days, no separate sale | City of Rancho Cucamonga Planning Department — Accessed 2026-09-20
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