Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Rancho Cucamonga ADU cost →Building an ADU in Rancho Cucamonga costs between $175,000-$350,000 for new construction, with per-square-foot costs averaging $250-$350. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $75,000-$150,000, while prefab/modular ADUs fall in between at $175,000-$350,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & 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. |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Rancho Cucamonga, where we have them — free, no obligation.
Get Rancho Cucamonga builder quotes →Permit fees in Rancho Cucamonga are 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.. The review timeline is 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)., with 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.. Impact fees are 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.. 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..
| 1-Bedroom Rent | $2,150-$2,300/month |
| 2-Bedroom Rent | $2,600-$2,750/month |
| Annual Rental Income (est.) | $26,700/year |
| Payback Period (est.) | 9.8 years |
| 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. |
| Overall ROI Estimate | 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 |
A typical ADU in Rancho Cucamonga generates approximately $26,700 per year in rental income based on average 1-bedroom rents. At an average construction cost of $262,500, the estimated payback period is 9.8 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Rancho Cucamonga and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Rancho Cucamonga: $75,000-$150,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $175,000-$350,000.
3. Pre-approved plans — available in Rancho Cucamonga, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
Tell us about your project and we'll pass it to ADU builders serving Rancho Cucamonga. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.