ADU Construction in Contra Costa County. Permitted. Built Right. Done.
DevCo Building Enterprises is a licensed general contractor based in Pacheco, CA, specializing in permitted ADU construction for homeowners and investors across Contra Costa and Alameda Counties. From the first site visit to your certificate of occupancy, we handle everything.
What Does ADU Construction Cost in Contra Costa County?
Most ADU projects in Contra Costa County run between $190,000 and $400,000 depending on unit size, design complexity, site conditions, and finish selections. Here's a rough breakdown by type:
6-10 months
5-9 months
Every project is different. The best way to get your real number is to schedule a site walk with Devin. We'll give you a straight estimate with no games.
What's Included in a DevCo ADU Build
We don't hand off pieces of a project. When you hire DevCo, you get one team, one point of contact, and full accountability from day one to move-in day.
Initial site consultation and feasibility assessment
Architectural design and permit documentation preparation
Full permit submission and county coordination with Contra Costa Building Inspection Division
Foundation, framing, roofing, plumbing, electrical, and HVAC
Interior finishes to your selected package
Final inspections and certificate of occupancy
Project walkthrough with Devin personally
The DevCo ADU Construction Process
We've worked with enough Contra Costa homeowners to know that the biggest frustration isn't the cost, it's the confusion. Here's exactly what working with DevCo looks like:
Site Assessment
Devin or a senior team member visits your property. We assess setbacks, utilities, access, and site conditions. You'll know what's feasible before anyone spends a dollar.
Design & Permitting
We prepare or coordinate your architectural drawings and submit to Contra Costa County. We manage every back-and-forth with the building department.
Construction
Licensed subcontractors work on your project under DevCo's direct management. You won't be surprised by who shows up.
Inspections & Closeout
We coordinate every required inspection, handle any correction notices, and walk you through the final unit before you sign off.
ADU Construction Across Contra Costa County
DevCo builds ADUs within a 15-mile radius of our Pacheco headquarters, covering the majority of Contra Costa and parts of Alameda County.
Concord, CA · our most active build market for detached ADUs
Martinez, CA · including waterfront and hillside properties
Walnut Creek, CA · in-fill lots, attached ADUs, and garage conversions
Pleasant Hill, CA · single-family lots adding rental income units
Lafayette, CA · higher-end detached ADUs and custom finishes
Orinda, CA · hillside setback-sensitive sites (we know the terrain)
Clayton, Oakland, Danville, Berkeley · within radius (call to confirm)
Frequently Asked Questions: ADU Construction
ADU construction in Contra Costa County typically costs $190,000-$400,000 depending on ADU type, size, and finish level. Garage conversions start lower ($90K+); new detached builds start around $220K. DevCo provides detailed line-item estimates so you know exactly what you're committing to.
Yes. All ADU construction in Contra Costa County requires permits through the County Building Inspection Division. State law (AB 68, SB 9, AB 2221) has streamlined the ADU permitting process significantly, but permits are still required. DevCo handles all permit prep, submission, and county coordination.
In Contra Costa County, most ADU projects take 6-12 months from permit submission to certificate of occupancy. Permit review typically takes 4-12 weeks depending on project complexity and county workload. DevCo tracks every stage and keeps you updated throughout.
Yes. Once you receive your certificate of occupancy, your ADU is legal to rent in California. Many of our Contra Costa clients begin renting within 30 days of project completion.
Yes. We work with property managers and investors adding ADUs to rental portfolios and investment properties throughout Contra Costa and Alameda Counties. We understand the ROI math and can help you structure the project to maximize rental yield.
Why Contra Costa Homeowners Choose DevCo for ADU Construction
There are ADU contractors who work across the whole state. DevCo works within 15 miles of Pacheco, which means we know your local inspectors, your county's specific permit requirements, and the setback rules for your specific neighborhood. That local knowledge saves you time and prevents the surprises that blow up projects.
Devin Grimes manages every project personally, no hand-offs to strangers
Full permit-to-certificate process handled in-house
Transparent estimate process, no hidden fees or surprise change orders
15-mile service radius, we're always nearby
Ready to Build Your ADU? Let's Start With a Site Assessment.
The fastest way to know if your project is feasible, and what it'll cost, is a site visit. Call Devin directly or fill out the estimate form and we'll schedule your walk within 48 hours.