Do You Need a Permit for a Retaining Wall in Brentwood, CA?

What the City of Brentwood code says

Chapter 17.660 of the Brentwood Municipal Code covers walls and fences. Section 17.660.008(I) covers retaining walls. We quote it directly (Brentwood Municipal Code §17.660.008, eCode360):

1. "Retaining walls shall not exceed a height of four feet."
2. "An embankment to be retained that is over four feet in height shall be benched so that no individual retaining wall exceeds a height of four feet above finished grade, and each bench has a minimum horizontal distance of two feet between each wall."
3. "An exception may be granted for a higher wall if necessary due to slope and/or soils, based on a geotechnical report from a licensed civil or geotechnical engineer, and approved by the chief building official or public works director."
4. "A building permit is required for retaining walls that are over four feet high (measured from the bottom of the footing to the top of the wall), and/or retaining walls supporting a steeply sloped surface called a surcharge."

What this means in plain terms

• Height limit: the standard is four feet per wall. Taller slopes are stepped into shorter walls with flat benches between them.
• Taller walls: a higher wall is an exception, supported by a geotechnical report and approved by the City's building or public works official.
• Permit: over four feet, measured from the bottom of the footing, or any wall that supports a surcharge such as a steep slope, needs a building permit.
• Why the footing matters: the permit height is measured from the bottom of the footing, so a wall that looks shorter above ground may still count.

The same chapter limits fence heights (the code lists 42 inches in front yards and up to seven feet on side and rear lines), which can matter when a fence sits on top of a wall. Ask the Building Division how the two combine on your lot.

Setbacks, property lines and HOAs

We haven't verified setback or property-line rules for retaining walls, so we don't state them. If your wall is near a property line, ask the City and talk to your neighbor first. If you're in an HOA, get architectural approval before work starts; HOA reviews can take weeks.

Other nearby jurisdictions

• Oakley: the City's building FAQ lists retaining walls "not over 4 feet in height measured from the bottom of the footing to the top of the wall" in its walls entry (City of Oakley). See Oakley.
• Unincorporated Contra Costa County (such as Discovery Bay): county handouts describe exemptions for retaining walls not over 3 ft from the top of the footing to the top of the wall, with conditions, and say terraced walls are limited to 3 ft per section (County handout, work not requiring a permit). That is the County, not Brentwood.
• Antioch: we haven't verified its retaining wall rules. See Antioch for where to ask.

Who pulls the permit, and what happens if no one does

Settle in the written scope who applies, who pays permit and plan-check fees, and who schedules inspections. Skipping a required permit is a red flag; ask any contractor who suggests it to put that in writing. We don't advise on the consequences of unpermitted work, but they can come up when you sell, refinance or insure the home.

Next steps: how to choose a contractor, what permits and engineering cost, or repairing an existing wall.