How to Compare ADU Contractors: A Side-by-Side Evaluation Guide

1. Project Experience and Fit

Look for contractors who have completed ADU projects similar to yours, not just general construction experience. A contractor with fifty custom home builds may have strong skills but limited familiarity with California's ADU-specific permitting process, ministerial approval requirements, or setback exceptions.

Questions to ask each contractor:

• How many ADU projects have you completed in the past two years?
• Have you built this ADU type (detached, garage conversion, prefab, JADU) before?
• Have you pulled permits in this specific city or county recently?

Local permitting experience matters. A contractor who works regularly with San Diego County, the City of San Diego, or your specific municipality will have process familiarity that can shorten permit review times.

2. Bid Scope and Clarity

A well-written ADU bid specifies what is and is not included. Look for:

• Line-item costs, not a single lump sum
• Clear handling of permit fees (included, estimated, or excluded)
• Explicit allowances labeled as allowances
• Site work and utility connections addressed
• Staging and material storage accounted for on your lot

Vagueness in bid scope becomes financial risk for you. Changes and add-ons after contract signing are one of the most common sources of ADU project disputes. A contractor who produces a detailed, itemized proposal is also showing you how they run their projects.

3. Proposed Timeline

Construction timelines in ADU bids often underestimate total project duration because they count construction days rather than calendar time. Ask each contractor for a timeline from permit submittal to final inspection, not just from construction start to completion.

In San Diego, permit review can take 4 to 12 weeks or longer depending on the city, project complexity, and current department workload. Some cities offer expedited review; others are running backlogs.

Additional questions to ask:

• When can you start the permit process?
• What is your current project load, and will this project overlap with others?
• How do you communicate with homeowners when delays come up?

4. License, Insurance, and Permit Responsibility

Verify each contractor's credentials before signing anything. California ADU contractors must hold a valid B (General Building) license from the California State License Board (CSLB). Specialty subcontractors for electrical, plumbing, and HVAC work must hold the applicable C-class license.

Insurance: ask for certificates of insurance showing general liability coverage and, if the contractor employs workers directly, workers' compensation. Ask to be named as an additional insured on the general liability policy.

Permit responsibility: confirm who will pull the permits. In California, the contractor of record who pulls the permit is legally responsible for the work meeting code. Some homeowners pull permits themselves as owner-builders, which transfers liability to them and can affect the property's resale history.

5. Communication and Working Relationship

How a contractor communicates before you sign a contract is usually how they communicate once work begins.

Notice during your pre-contract interactions:

• How quickly do they respond to messages and calls?
• Do they answer your questions directly, or rush past them?
• When something in their bid is unclear, are they open to explaining it in detail?
• Do they proactively flag things you might not have thought to ask about?

ADU projects typically run 6 to 18 months from start to final inspection. A contractor who is hard to reach or dismissive of your questions during the sales process will likely be harder to reach once your deposit is in and materials are on order.

6. Price (Evaluated Last)

Once you have confirmed that each bid covers a comparable scope of work, look at price. Meaningful price differences at that point usually reflect one of the following:

• Overhead and margin: Larger firms carry higher overhead. Smaller firms may have lower costs but less redundancy if a problem arises mid-project.
• Subcontractor relationships: Some contractors have long-term relationships with reliable subcontractors and better pricing on labor and materials.
• Local permitting experience: Contractors who work regularly in your area may have faster, lower-cost permit processes due to established relationships with plan checkers.
• Materials and finishes: The bid may specify different fixture grades, insulation levels, or structural approaches that affect durability and future maintenance.

The lowest bid is not automatically the best value, and the highest is not automatically the safest choice. Look at what each price actually covers and what each contractor's track record suggests about their ability to deliver it.