Custom ADU Builders in The Inland Empire
At ADUs by Avatar, we help homeowners throughout the Inland Empire ( including Riverside & San Bernardino Counties ) plan, design, permit, and build ADUs with a clear process from start to finish.
ADU Builder in the Inland Empire, CA
Building an ADU in the Inland Empire is one of the best ways to add living space, increase property value, and create long-term flexibility for your household. Whether you’re planning a detached backyard ADU, converting a garage, or exploring a junior ADU (JADU), the process can feel overwhelming without the right team guiding you.
The Inland Empire includes both Riverside County and San Bernardino County, and while California state law provides baseline ADU rules, individual cities may still have their own development standards and permit requirements.
Why Inland Empire Homeowners Are Building ADUs
Homeowners across the Inland Empire are building ADUs for a wide range of reasons, including:
- Creating long-term rental income
- Building a unit for aging parents or adult children
- Adding a private guest suite or home office
- Increasing resale value with legal square footage
- Converting unused garages into livable space
With larger lot sizes in many Inland Empire neighborhoods, ADUs can be an especially strong option for homeowners who want to maximize their property.
Types of ADUs Allowed in the Inland Empire
Depending on your property, zoning, and city requirements, you may be eligible for one or more ADU types:
Detached ADUs
A standalone backyard unit that offers the most flexibility in layout and long-term use.
Attached ADUs
An ADU connected to the primary home, often built as an addition.
Garage Conversions
One of the most common and cost-effective ADU options, especially on properties with detached garages.
Junior ADUs (JADUs)
A smaller unit (typically up to 500 sq ft) created within the existing home footprint.
ADU Permits in the Inland Empire
All ADUs require permits, and most projects require a combination of building, electrical, plumbing, and mechanical approvals.
Most Inland Empire ADU projects require:
- Building permits
- Electrical permits
- Plumbing permits
- Mechanical/HVAC permits
- Title 24 energy compliance
- Structural engineering (depending on scope)
The exact process varies depending on whether your property is in a city jurisdiction or an unincorporated county area.
ADU Costs in the Inland Empire
The cost to build an ADU in the Inland Empire depends on factors such as:
- Detached build vs garage conversion
- Unit size and layout
- Utility locations and trenching needs
- Site access and grading
- Finish level (standard vs custom)
- Engineering and structural requirements
In many cases, garage conversions can be a more cost-effective option, while detached ADUs provide the most flexibility in design and long-term value.
ADU Timeline in the Inland Empire
Most ADU projects follow a similar timeline:
- Feasibility + Site Review
- Design + Floor Plan Development
- Engineering + Title 24
- Permit Submittal + Plan Check
- Construction + Inspections
- Final Approval + Move-In
Permit timelines can vary depending on city plan check workload and the complexity of the project.
Why Homeowners Choose ADUs by Avatar
ADU construction requires more than a typical remodel. It involves permitting, code compliance, inspections, and careful project management.
When you work with ADUs by Avatar, you get:
- A clear step-by-step process
- ADU-specific experience
- Design-build support from start to finish
- Honest pricing and realistic timelines
- A team experienced across Southern California
Cities We Serve in the Inland Empire
We build ADUs throughout Riverside County and San Bernardino County, including:
Riverside County
- Corona
- Riverside
- Eastvale
- Norco
- Temecula
- Murrieta
- Lake Elsinore
- Menifee
San Bernardino County
- Ontario
- Rancho Cucamonga
- Fontana
- Redlands
- San Bernardino
- Chino
- Chino Hills
- Upland
Not sure which jurisdiction your property falls under? We can help confirm during your initial consultation.