ADUs in Rancho Cucamonga
Backyard homes for Rancho Cucamonga, priced before you sign.
We design, permit and build standard ADU models in Rancho Cucamonga and across the Inland Empire. You pick a model, we assess your lot, and you get one all-in price before you sign.
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The models
Four standard homes, each with a price up front.
Starting prices include design, permitting and construction with standard finishes. Site work and utilities generally run $15,000 to $35,000 and are priced after we see your lot, and city permit fees are billed at cost. All four are under the City's 1,200 sq ft limit for its own ADUs. See what's included.
Around the Inland Empire
Buildoly projects in the western Inland Empire.
Each pin is a Buildoly project between Ontario and Riverside. See the full map.
Rancho Cucamonga ADU rules in plain English
What you can build in the City of Rancho Cucamonga.
The basics for a single-family lot in Rancho Cucamonga, under the ADU chapter the City rewrote in December 2025. Every lot is different, so we confirm each of these for your address before we price anything.
How many
An ADU and a junior ADU, or more
Under the state-law rules in the City's code, you can build an ADU and a junior ADU inside the house or an existing accessory building, or a new detached ADU of up to 800 sq ft with a junior ADU. The City also allows its own ADUs of up to 1,200 sq ft. The code doesn't say how many can share one lot, so we confirm the total with Planning.
Dev. Code 17.100.040.A-B; 17.100.060Size
Up to 1,200 sq ft
A City-standard detached ADU can be up to 1,200 sq ft. An attached one is held to half the house or 1,200 sq ft, whichever is less. The state-law detached ADU is capped at 800 sq ft.
Dev. Code 17.100.060.F, Table 17.100.050-1; 17.100.040.B.1Height
16 ft detached, 25 ft attached
A detached ADU can be 16 ft tall, or 18 ft within a half mile of a major transit stop, and 20 ft there to match the house's roof pitch. An attached ADU can be 25 ft.
Dev. Code Table 17.100.050-1, notes (2)-(4); 17.100.040.B.2-3Setbacks
4 ft from the side and rear
The front follows the zone's setback, unless that would rule out an 800 sq ft ADU. An ADU inside an existing structure, or rebuilt in the same place and size, needs no setback.
Dev. Code 17.100.060.H.1-3Parking
One space for a new detached ADU
A new City-standard detached ADU needs one space, unless it's within a half-mile walk of transit, within a block of a car share station, in a historic district, or where street permits aren't offered. The state-law ADUs and a junior ADU need none, and a garage converted or torn down for the ADU doesn't have to be replaced.
Dev. Code 17.100.060.I.1-5; 17.100.070.FOwning and renting
Rent for more than 30 days
You don't have to live on the property to have an ADU. Rentals must run more than 30 consecutive days, and an ADU can't be sold apart from the house except under the nonprofit conditions in the code.
Dev. Code 17.100.090.A-CWorth knowing in Rancho Cucamonga
The City's code requires the owner to live in the house or the junior ADU. State law now requires that only when the junior ADU shares a bathroom with the house, so we confirm which standard the City applies to your plan.
The City posts pre-approved detached ADU plans, and an application using one must be approved or denied within 30 days. On a lot of 20,000 sq ft or more, the City may allow an additional ADU.
Changing on January 1, 2027
SB 1117 limits the impact fee on an ADU over 750 sq ft to the area above 750 sq ft, in proportion to the main house, for up to two ADUs on a lot. ADUs of 750 sq ft or less still pay no impact fee.
AB 956 lets you build two new detached ADUs on a single-family lot through the state's approval path. On that path a city can cap each one at 800 sq ft.
Sources: Rancho Cucamonga Development Code Chapter 17.100, as restated by Ordinance No. 1049, adopted December 3, 2025, in effect January 2, 2026; HCD letter to the City of December 5, 2025; California Government Code sections 66310 to 66342; SB 1117 and AB 956 (2026). Checked November 2026.
How it works
From your lot to move-in.
Step 1
Pick a model
Choose a model and finishes online, or book a free consultation to talk it through.
Step 2
Site assessment
We visit your lot, check utilities, access and the City's rules, and give you one all-in price before you sign.
Step 3
Design and permits
We finish the plans and run the permit with the City of Rancho Cucamonga from submittal to approval.
Step 4
Build and move in
We build on site and manage the job through final inspection and your certificate of occupancy.
Typical timeline: 8 to 12 months from start to finish. About 1 month of design, 2 to 4 months of permits and 3 to 5 months of construction. Your lot and the City's review times can move it.
Rancho Cucamonga ADU questions
What Rancho Cucamonga homeowners ask us.
Our models start at $165,000 for Model S, $195,000 for Model 1, $270,000 for Model 2, $360,000 for Model 3. Those are all-in starting prices for design, permitting and construction. Site work and utilities generally run $15,000 to $35,000, and we price yours after the site assessment, before you sign. City permit fees are separate: your city sets them and we bill them at cost. You start with $1,000, credited in full to your contract, and many of our clients finance the whole build through our lending partners, subject to credit approval. See what's included in the price.
A City-standard detached ADU can be up to 1,200 sq ft, and an attached one up to half the house or 1,200 sq ft, whichever is less. A detached ADU built under the state-law rules in the City's code is capped at 800 sq ft. All four of our models are under 1,200 sq ft. We check the exact limit for your lot.
Our typical timeline is 8 to 12 months from start to finish: about 1 month of design, 2 to 4 months of permits and 3 to 5 months of construction. Your lot and the City's review times can move it either way, and we give you a schedule for your address after the site assessment.
Only for a new City-standard detached ADU, and only if no exception applies. It needs no space within a half-mile walk of public transit, within one block of a car share station, in a historic district, or where on-street permits are required but not offered to the occupant. ADUs built under the state-law rules and junior ADUs need none, and a garage or carport converted or torn down for the ADU doesn't have to be replaced.
You can rent it out for more than 30 consecutive days, and you don't have to live on the property. An ADU can't be sold separately from the house, except under the nonprofit and affordability conditions in the City's code.
Yes. We build across the Inland Empire, as well as Los Angeles County, Orange County and San Diego. Each city has its own ADU rules and plan check, and we confirm them for your address. Enter your address in our quote tool to check that you're in our service area.
Where we build
We also build in these cities.
Each city page covers that city's ADU rules and who issues the permit. All cities.
Los Angeles County
Orange County
San Diego County
See your price for a Rancho Cucamonga ADU.
Pick a model and tell us your address. After the site assessment you get one all-in number, before you sign.