How to Get a Building Permit in Contra Costa County: A Homeowner’s Guide

Planning a remodel, addition, or Accessory Dwelling Unit (ADU) in Contra Costa County? One of the most important steps before construction begins is securing the right permits. The permitting process helps ensure your project meets building codes, safety standards, and local zoning requirements.

While it can feel overwhelming, a little preparation goes a long way. This guide will walk you through what to expect, what documents you’ll need, and how to avoid common mistakes.

Which Projects Require a Permit?

If you’re wondering whether your project requires a building permit, here are some of the most common examples in Contra Costa County:

Kitchen and bathroom remodels involving plumbing or electrical changes.
Structural modifications (removing or adding walls).
Room additions and garage conversions.
New Accessory Dwelling Units (ADUs) or Junior Accessory Dwelling Units (JADUs).
Replacing windows or doors with different sizes.
Upgrading electrical service panels or HVAC systems.

If you’re unsure, it’s always best to check with the Contra Costa County Building Department or consult a professional before starting any work. Starting without a permit can lead to fines, delays, and expensive corrections. And remember, the Planning and Building Departments are there to help you. It’s their job to ensure your project is completed safely so working with them is to the homeowner’s advantage.

Tip: A remodel that doesn’t move walls, doesn’t include adding plumbing or electrical fixtures, and doesn't move any exterior doors or windows or siding most likely won’t need a planning permit. It may need a building permit only so the building inspector will know the scope of work when he is on site.

What Documents Do You Need?

Every project is unique, but most residential permit submittals require:

As-Built Drawings: Accurate plans of your existing home layout.
Proposed Floor Plans: Showing all changes, new walls, and dimensions.
Elevations: Exterior views if you’re modifying openings or adding space.
Site Plan: Showing property lines, setbacks, existing structures, neighbor’s homes, and any easements.
Title 24 Energy Calculations: Required for many remodels and all additions.
Structural Calculations: If you’re removing or adding load-bearing walls.

For projects involving electrical or plumbing upgrades, you may need additional diagrams and specifications. One of the most common reasons plans are rejected is missing or incomplete information.

The Permitting Process Step-by-Step

Here’s a typical process for residential permits in Contra Costa County:

Step 1 - Pre-Design

Before you begin drawing anything, it’s important to document existing conditions accurately. This includes measuring each room, noting ceiling heights, recording window and door sizes, and photographing key details. As-built plans provide the baseline for all future work.

Step 2 - Develop Design Documents

You can begin exploring design options once you have a clear record of what exists. This is when proposed floor plans and elevations are drafted to show exactly what you intend to build. If your project involves structural work, you’ll coordinate with an engineer to prepare calculations and framing details.

Step 3 - Submit Your Application

Permit applications are submitted to the Contra Costa County Building Department along with all required plans and forms. You’ll also pay plan check and permit fees at this stage. Most local jurisdictions have their own Planning Departments, so check with your local town’s website or give them a call. Some larger towns have the resources to support their own Building Department and don’t need to rely on the County’s services. Knowing which department to submit to will save you time and effort.

Step 4 - Plan Review

The County reviews your plans for code compliance, structural safety, and energy efficiency. You may receive comments requesting clarifications or revisions.

Step 5 - Permit Issuance

Once all comments have been addressed, your permit is issued. Work can begin once your permit card is posted on-site. Work is not allowed to begin until the permit has been issued.

Step 6 - Inspections

During construction, County inspectors will visit to verify that the work matches the approved plans. Inspections typically cover framing, rough plumbing and electrical, insulation, and final sign-off. Depending on the complexity of the project, there may be more inspections required. If a structural or geotechnical engineer is involved there will most likely be periodic inspections performed to review that portion of the work.

Common Pitfalls to Avoid

Over the years, I’ve seen many projects delayed because of avoidable mistakes. Here are a few to watch for:

Submitting plans without confirming zoning requirements, especially for ADUs and additions.
Forgetting Title 24 energy forms or incomplete energy documentation.
Underestimating lead times for structural engineering and plan revisions.
Assuming a small remodel doesn’t need permits (almost all do if you’re moving plumbing, electrical, or walls).

The more thorough your plans, the smoother your process will be

How I Help Homeowners in Martinez and the East Bay

I work with homeowners throughout Contra Costa County to prepare complete, accurate permit submittal packages. My services include:

Precise as-built measurements and existing conditions plans.
Drafting clear proposed layouts, elevations, and details.
Coordinating with engineers if needed.
Preparing documentation for Title 24 compliance.
Submitting plans and responding to County plan check comments.

The goal is to reduce delays, avoid surprises, and give you the peace of mind that your project is compliant and ready to build.

Ready to Get Started?

If you’re planning a remodel, addition, or ADU in Martinez or anywhere in Contra Costa County, I’d be glad to answer questions about the permitting process or help you prepare a scope of services. Reach out to schedule a consultation or learn more about how I can help set your project up for success.