ADU · Costs
How Much Does an ADU Cost in the Inland Empire?
Transparent pricing from a licensed IE general contractor. No surprises.
Starting From
$200,000 — All-In
Most Inland Empire ADU projects range from $200,000 to $435,000 depending on size, site conditions, and finish level.
Cost Breakdown
Cost To Build a New Detached ADU
Inland Empire, California
| Type | Size | Vertical Build Cost | Build Cost/sqft | Typical All-In Cost | All-In/sqft |
|---|---|---|---|---|---|
| Studio / 1BA | 400 sq ft | $150K | $375 | $200K | $500 |
| 1BR / 1BA | 500 sq ft | $175K | $350 | $235K | $470 |
| 1BR / 1BA | 650 sq ft | $210K | $323 | $275K | $423 |
| 2BR / 1BA | 750 sq ft | $233K | $310 | $300K | $400 |
| 2BR / 2BA | 900 sq ft | $270K | $300 | $345K | $383 |
| 2BR / 2BA | 1,000 sq ft | $295K | $295 | $375K | $375 |
| 2BR / 2BA | 1,200 sq ft | $348K | $290 | $435K | $363 |
*Vertical build cost covers framing, roofing, insulation, drywall, windows, doors, electrical, plumbing, HVAC, and standard finishes. All-in cost adds design, engineering, permits, sitework, and utility connections.
What's Included
Inside your all-in cost.
📐
01
Design & Engineering
$8,000 – $12,000
Architectural plans, structural engineering, and Title 24 energy compliance.
🏛️
02
Permit Fees
Varies by city
Impact fees waived for ADUs under 750 sq ft. Larger units: $2–8/sq ft depending on city.
🚜
03
Sitework & Grading
$15,000 – $40,000
Foundation prep, grading, and drainage. Flat lots cost less. Sloped lots cost more.
🔌
04
Utility Connections
$5,000 – $25,000
Water, sewer, and electrical connections to existing services. Long runs cost more.
🏗️
05
Vertical Construction
$290 – $375/sq ft
Full stick-built construction including all systems and standard finishes.
🚿
06
Finishes & Fixtures
Included in vertical cost
Standard package included. Premium upgrades available at additional cost.
Compare
Garage conversion vs new construction.
| Garage Conversion | New Construction | |
|---|---|---|
| Cost range | $80,000 – $150,000 | $200,000 – $435,000 |
| Timeline | 3–5 months | 6–10 months |
| Permits | Simpler | Full permit set |
| Size limit | Existing garage size | Up to 1,200 sq ft |
| Best for | Budget-conscious | Maximum rental income |
FAQ
Questions, answered.
Flat lots need minimal grading. Sloped lots require retaining walls, extra excavation, and engineered foundations — all of which add to sitework cost.
Get An Estimate
Every project is unique.
These are typical ranges based on current Inland Empire market conditions as of 2026. Schedule a free feasibility consultation to get a detailed estimate for your specific property.