ADU Builders in Ontario, California
Families across Ontario are using accessory dwelling units to solve multigenerational living and generate rental income. As full-service ADU builders, we take Ontario projects from feasibility to final inspection — designed for the hot, dry summers where cooling loads drive design.
Typical cost
$143k–$314k
Permit time
6–10 weeks
Est. rent
$1,600+/mo
Population
180,000
Popular ADU types in Ontario
Our most requested projects in Ontario are junior ADUs (JADUs) and garage conversions. Newer subdivisions in Ontario often have tighter side yards, so we frequently recommend attached ADUs or converting an existing garage to keep costs down.
Design-wise, Ontario homeowners in the Inland Empire tend to favor stucco-and-tile ranch styles, cool roofs and shaded patios.
Building an ADU in San Bernardino County
Every Ontario ADU we build is engineered around local conditions — especially summer heat, larger lots with long utility runs and wildfire zones. We prepare complete plan sets so the city can approve within the state's 60-day review window, typically 6–10 weeks here.
At $1,600–$2,450 per month in rent, a new ADU in Ontario can pay for itself in roughly 9.4 years.
Ontario ADU FAQs
How much does it cost to build an ADU in Ontario?
Most Ontario ADUs we build land between $143k and $314k, depending on size, site work and finishes. Garage conversions sit at the low end; custom two-story units at the high end.
How long does ADU permitting take in Ontario?
State law requires cities to act on complete ADU applications within 60 days. In practice, Ontario permits typically take 6–10 weeks when plans are submitted complete — which is what our in-house drafting team focuses on.
What can I rent an ADU for in Ontario?
Based on Inland Empire rental trends, a new 1-bedroom ADU in Ontario commonly rents for $1,600–$2,450 per month, putting typical payback around 9.4 years.
What are the biggest challenges for ADUs in Ontario?
In Ontario and the wider Inland Empire, the issues we plan around most are summer heat, larger lots with long utility runs and wildfire zones. We review these during a free feasibility check before you commit.
Is junior ADUs (JADUs) a good option in Ontario?
Yes — junior ADUs (JADUs) are among the most popular projects we build in Ontario. Corner lots and alley-access lots in Ontario are ideal for ADUs with their own street entrance and separate address.
ADU builders near Ontario
Get a free ADU feasibility check in Ontario
Tell us about your lot. We'll review zoning, setbacks and utilities and send a ballpark budget — no obligation.