Building an ADU in Brea
In Brea, successful ADU planning starts with understanding how local requirements impact design, access, and utilities. We help homeowners assess what’s allowed, identify potential challenges early, and develop a plan that aligns with both the property and city expectations.
Our design-build process keeps each phase organized and predictable, from documentation and permits to construction and final approval. With clear timelines and consistent communication, we help turn your ADU plans into a finished space that adds real functionality and value.
ADU Services Available in Brea, CA
Our ADU services in Brea are built around clarity and coordination. From feasibility and design to permits and final construction, we help homeowners avoid common setbacks and move forward with a well-structured design-build process.
✅ Detached & Attached ADUs
✅ Garage Conversion ADUs
✅ Junior ADUs (JADUs)
✅ ADU Planning & Design Coordination
✅ Permits, Plan Submittals & City Revisions
✅ Construction, Inspections & Final Completion
A free site evaluation helps confirm feasibility and outlines the best path forward for your ADU project.
ADU Rules in Brea
ADUs allowed per lot
1 conversion ADU + 1 new ADU + 1 JADU
Max detached ADU size
Up to 1,200 sq ft
Max attached ADU size
Up to 1,200 sq ft or 50% of the main home, whichever is less
Max JADU size
Up to 500 sq ft
Max height (detached)
16 ft (more where state law allows)
Two-story ADU
Attached ADUs up to 25 ft; over a second floor, can match the main home's height
Setbacks
4 ft side and rear; detached ADU must sit behind the front of your house
Space between buildings
10 ft from the main house; garage conversions and accessory buildings exempt
Parking
State exemptions apply (transit, conversions, garage conversion); we confirm the city requirement
Owner occupancy
Not required for an ADU (JADU sharing a bathroom requires the owner on site)
Short-term rental (Airbnb)
30-day minimum rental; no Airbnb
Impact fees
None under 750 sq ft; larger ADUs pay proportionally
Pre-approved plans
City program exists; we check availability for your property
Permit review
Building & Safety plan check; no separate planning application
Approval timeline
60 days after a complete application
Local insight
Brea requires a detached ADU to sit behind the front of your house and 10 ft away from it. Hillside, high fire hazard, and flood areas have extra restrictions, so we check your parcel first.
How ADU Permitting Works in Brea
In Brea, your ADU goes through the Building & Safety Division’s plan check, with no separate planning application and no public hearing. The city also runs a pre-approved ADU program in which designers have their plans approved by the city and then list them for homeowners. Properties in a methane zone or flood zone can’t use it, and hillside, very high fire hazard, and liquefaction zones may have extra restrictions. If you’re replacing a detached garage, the demolition permit is reviewed with your ADU.
Property feasibility review
Review zoning, lot conditions, access, utilities, and applicable ADU requirements.
ADU design and preparation
Prepare the site plan, architectural drawings, engineering, and required supporting documents.
City plan review and approvals
Submit the application, coordinate with city departments, and respond to plan-check corrections.
Permit issuance and construction
After approval and permit issuance, proceed with construction and required inspections.
FAQs About ADUs in Brea
Is my property eligible for Brea’s pre-approved ADU program?
Possibly. Properties in a methane zone or flood zone can’t use the program, and hillside, very high fire hazard, and liquefaction zones may have extra restrictions. We check your parcel and tell you whether a pre-approved plan is available and worth using.
Can I use custom ADU plans instead of pre-approved plans in Brea?
Yes. Custom plans go through the same Building & Safety plan check. A custom design lets us fit the ADU to your lot, including the rule that a detached ADU sits behind the front of your house.
What documents are required to submit an ADU permit application in Brea?
You submit your plans to Building & Safety for plan check along with the city’s application fee. A typical plan set includes a site plan, floor plans, elevations, and structural and energy documents, plus a demolition permit if you’re replacing a detached garage. A JADU also needs a recorded covenant. We confirm the current checklist with the city and prepare the package.
Can I convert an existing garage into an ADU in Brea?
Yes. Converted garages and accessory buildings are exempt from Brea’s 10 ft separation rule, and state law removes replacement parking requirements for garage conversions. We check the structure and your lot’s hazard zones first.
How can Lamarc Prime Builders help with ADU design, permitting, and construction in Brea?
We handle the whole project in one place. We start with a feasibility review of your lot, prepare the design, drawings, and engineering, submit to Brea’s Building & Safety Division and respond to plan-check corrections, and then build your ADU through final inspections.
