Permit guides

ADU Permits in Brentwood: a Homeowner's Guide

Brentwood reviews ADUs against objective design standards — and many neighborhoods sit inside specific plans with their own rules.

Last updated October 2026. Rules change; always confirm current requirements with the city before you build.

Who handles your permit

ADU permits in Brentwood run through the Community Development Department. Approval is ministerial — no discretionary review — but the design has to satisfy the city's Objective Design Standards for Residential and Mixed-Use Projects, which the council has been updating (most recently in 2025).

What you can build

The Brentwood baseline:

1,200 sq ftMax for a detached ADU

16 ftHeight limit for most detached ADUs

4 ftMinimum rear and side setbacks

1 + 1One ADU plus one Junior ADU per single-family lot

ObjectiveDesign standards apply — no discretionary review

60 daysDeadline to act on a complete application

Where a specific plan, planned development, or neighborhood plan covers the property, the design must also conform to that plan in all significant respects.

Specific plans change the game

Brentwood is a city of master-planned neighborhoods, and that's the local wrinkle: if your property sits in an area with an adopted specific plan, planned development, or precise plan, your ADU has to conform to it on top of the base zoning and the objective design standards.

Landscaping, screening, parking, and usable open space requirements all get checked against the underlying plan. Before designing, confirm which plan (if any) governs the lot — it determines which standards actually apply.

Find your plan first. In Brentwood, the specific plan covering the lot matters as much as the base zoning — check it before spending on design.

What goes into the submittal

A typical Brentwood submittal includes:

Building permit / plan check application
Site plan, floor plans, elevations (existing and proposed)
Structural calculations and Title 24 energy compliance
Objective design standards compliance documentation
Electrical, plumbing, and mechanical layouts

Where applications usually get stuck

Specific-plan overlays. Extra standards that don't exist in the base zoning.
Landscaping and screening. Reviewed against the plan, not just the code minimum.
Design standard details. Objective doesn't mean loose — every standard gets checked.
HOA CC&Rs. Many Brentwood neighborhoods have HOAs; they can't prohibit ADUs but may impose standards.

Not sure where to start? That's the part we do. We look at your property, map the requirements, coordinate the plans and specialists, and manage the submittal and corrections — one point of contact.

Tell us what you need help with.

Not sure where to start? That's what we're here for.

Send your project

Erik — (916) 540-8960 · Vall — (916) 956-8106
office@pcg-engineering.pro