Building an ADU is a major investment—typically $150,000-$350,000+. Choosing the right contractor is critical to your project's success. Here are the top 5 things to look for when searching for the best ADU builders in San Diego.

1. Valid California Contractor License

This is non-negotiable. Always verify your contractor's license before signing anything.

How to Verify

Visit CSLB License Lookup
Confirm license is active and in good standing
Check for any complaints or disciplinary actions
Verify workers' compensation insurance

For ADU construction, look for:

Class B - General Building Contractor
Or appropriate specialty licenses (C-10 Electrical, C-36 Plumbing, etc. if subcontracting)

2. ADU-Specific Experience

ADU construction has unique requirements. Ask potential contractors:

How many ADUs have they completed in San Diego?
Can they show you completed projects?
Are they familiar with San Diego Development Services?
Do they handle permits or do you?
What's their typical timeline for ADU projects?

3. In-House Capabilities

The best ADU builders handle most work in-house rather than subcontracting everything. Benefits include:

Better coordination: One team, one schedule
Clear accountability: No finger-pointing between subs
Consistent quality: Same standards throughout
Faster timelines: No waiting for subcontractor availability

At One Stop Builders, we have licensed plumbers, electricians, framers, and finish carpenters on our team.

4. Transparent Pricing and Contracts

Quality ADU builders provide:

Detailed, itemized estimates (not lump sum)
Clear allowances for selections (cabinets, fixtures, etc.)
Written contracts specifying scope, timeline, and payment schedule
Process for handling change orders
Warranty information

Red Flags to Watch For

Requests for large upfront payments (more than 10%)
Vague or verbal-only estimates
Pressure to sign quickly
Significantly lower bids than competitors (too good to be true)
No physical office or references

5. Portfolio and References

Review their previous work:

Ask for photos of completed ADUs
Request references from recent clients
Check online reviews (Google, Yelp, Houzz)
Visit a completed project if possible

Questions for References

Was the project completed on time?
Was the final cost close to the estimate?
How was communication during the project?
How did they handle problems that came up?
Would you hire them again?

Why One Stop Builders?

We check all the boxes:

✓ California Licensed Contractor #1101128
✓ 15+ years residential construction experience
✓ All trades in-house
✓ Transparent, itemized estimates
✓ Strong portfolio of completed San Diego ADUs
✓ 5-star reviews from real clients

Call (858) 567-0007 for a free ADU consultation.

Best ADU Builders in San Diego: Top 5 Things to Look For