How to Choose the Right Contractor for Your ADU in Southern California

Jan 21
3 min read

Building an accessory dwelling unit (ADU) in Southern California is exciting — whether it's a garage conversion, backyard cottage, or attached suite. But choosing the right contractor is key to avoiding delays, budget overruns, or poor workmanship. With high demand in counties like Riverside, San Bernardino, Orange, and Los Angeles, there are many options, but not all are reliable.

The wrong contractor can turn your project into a nightmare. In 2026, with strict Title 24 energy rules, seismic requirements, and permitting timelines (60–120 days), you need someone experienced. Here's a step-by-step guide to choosing the right contractor for your ADU in Southern California, based on real client stories and industry tips.

Step 1: Verify Licensing & Insurance (First Thing)

License Check: All contractors in California must have a Class B (General Building) or Class C (specialty) license from the CSLB (Contractors State License Board). Search CSLB.ca.gov for their license number, complaints, and status.
Bond & Insurance: Confirm workers' comp, liability insurance ($1M+), and a $15,000 bond. This protects you from accidents or unfinished work.
Tip: Avoid unlicensed "handymen" — they can't pull permits for ADUs, and Title 24 compliance requires pros.

Michael's Drafting recommends licensed contractors who've worked with our permit-ready plans in Fontana, Moreno Valley, and other areas.

Step 2: Get Multiple Bids & Check References (2–4 weeks)

Bids: Get 3–5 bids from contractors specializing in ADUs. Provide them with detailed plans (Michael's Drafting supplies permit-ready sets to make bidding accurate).
References: Ask for 3–5 recent client references in Southern California. Call them — ask about timeline, quality, communication, and any issues with permits or Title 24.
Portfolio: Review past ADUs in similar counties (e.g., Riverside for inland, Orange for coastal). Look for structural quality, finishes, and code compliance.
Tip: Low bids often mean shortcuts — aim for mid-range with strong references.

Step 3: Evaluate Experience & Specialization

ADU Experience: Choose contractors with 5+ years in ADUs — they know Title 24, seismic design, fire separation, and county rules (e.g., faster in San Bernardino vs. stricter in LA).
Subcontractors: Ask about their team for plumbing, electrical, structural — ensure they're licensed.
Permits: Good contractors handle permitting or work closely with drafters like Michael's Drafting for quick approvals.
Tip: Structural knowledge is crucial for two-story or detached ADUs — check if they handle shear walls and foundations.

Step 4: Review Contracts & Costs

Contract Details: Written contract with timeline, payment schedule (never 100% upfront), materials, change order process, warranty (1–2 years).
Costs: Expect $100,000–$500,000+ for ADUs. Get itemized bids — drafting ($3,500+), permits ($5,000–$20,000), Title 24 upgrades ($10,000–$30,000), construction.
Payment: 10–20% deposit, progress payments, final on completion.
Tip: Budget 10–20% contingency for surprises. Michael's Drafting's accurate plans reduce change orders.

Step 5: Watch for Red Flags

No license or insurance.
Pressure for full upfront payment.
Vague timelines or no references.
Unfamiliar with Title 24 or local codes (e.g., setbacks in Rancho Cucamonga).
Low-ball bids that seem too good (often mean subpar work).

Final Tips for a Smooth ADU Build in Southern California

Start with strong plans — Michael's Drafting creates permit-ready drafting to speed up the process.
Coordinate with your contractor early for Title 24 reports and structural details.
Check CSLB complaints and BBB ratings.
Get everything in writing — protect yourself.
Focus on local contractors — they know county inspectors in San Bernardino or Riverside.

Choosing the right contractor ensures your ADU is built right, on time, and within budget.

Ready to plan your ADU? Contact Michael's Drafting for permit-ready plans, Title 24 compliance, and expert guidance in Southern California. Free consultation – call 909-486-3789 or email info@michaelsdrafting.com today.