ADU Builder in Huntington Beach, CA
Huntington Beach issued building permits for 115 ADUs in 2024 and 87 in 2025, according to the City’s annual housing reports to the state. If you’re planning a backyard cottage, a garage conversion or a junior unit inside the house, one detail sets the city apart: Huntington Beach’s own ADU section (HBZSO Section 230.10) is no longer in effect. The City says state ADU and JADU law, effective January 1, 2020, now governs, and it reviews every ADU and JADU ministerially.
ADUs in Surf City: what the rules look like today
Orange Home Builders is a licensed design-build contractor (CSLB #1117595, class B) based in Newport Beach. Our design team produces 3D designs and construction drawings, we take care of permits and HOA paperwork, and a project manager runs each build.
Two routes: the City's pre-approved plan or a custom design
The HB Pre-Approved ADU Plan
Under Assembly Bill 1332, the City offers its own HB Pre-Approved ADU Plan: a one-story, detached, 490 sq ft unit. It saves design time, but the City is clear that modifications or deviations aren’t allowed. It works well when your yard fits the footprint and you’re happy with the layout as drawn. We can still handle the site plan, utility runs, foundation and construction around it.
A custom ADU
When you want a second bedroom, a unit attached to the house, or a garage conversion, a custom design is the way to go. State law, summarized in HCD’s ADU Handbook, sets the outer limits a city can’t go below:
- Size: a city can’t set a maximum below 850 sq ft (studio or one bedroom) or 1,000 sq ft (more than one bedroom).
- The 800 sq ft floor: an ADU of up to 800 sq ft, 16 feet tall, with 4-foot side and rear setbacks, can’t be blocked by lot coverage or floor-area rules.
- Height: at least 16 feet for a detached unit, 18 feet within a half-mile of major transit (plus up to 2 more feet to match the roof pitch of the main house).
- Conversions: converting existing space, such as a garage, isn’t subject to the size limits.
Our ADU and additions page explains how we design both kinds of unit.
Coastal Zone properties
The City notes that development in the Coastal Zone may require a Coastal Development Permit. HCD’s handbook says local agencies must approve or deny an ADU’s CDP within 60 days of a complete application. We confirm your parcel’s coastal status first, so the CDP runs alongside design instead of after it.
Methane districts and fire plan check
The Huntington Beach Fire Department publishes a Methane District Map and a matching GIS layer showing where methane districts sit in the city. Building in a methane district can add a separate fire permit, and the Fire Department’s application types include Methane Barrier and methane detection records.
How fire plan check works, per the Fire Department:
- Applications are filed through the City’s Accela Citizen Access portal and require a valid contractor license.
- Plan review targets are 20 business days for a first review, 10 for a resubmittal and 5 after that.
We map your lot against the methane districts during feasibility, so any barrier or detection design is in the first submittal.
Who's building ADUs here
The Census Bureau reports that 55.4% of Huntington Beach homes are owner-occupied, and 19.4% of residents are 65 or older. Many ADU conversations here are about multigenerational living: a parent moving into a ground-floor unit, or an adult child living close by. State law no longer lets cities require owner-occupancy for an ADU, and cities can require rentals to be longer than 30 days.
Working hours on a permitted job
With a valid City permit, construction is allowed from 7:00 a.m. to 7:00 p.m., Monday through Saturday. Work isn’t allowed on Sundays or federal holidays. We share the schedule with you before the foundation pour, so neighbors aren’t surprised.
Our ADU process
- Feasibility. Coastal status, methane district, utilities and yard space.
- Plan choice. The City’s 490 sq ft plan or a custom 3D design.
- Permits. Ministerial ADU review, CDP when required, and fire plan check.
- Construction. A project manager coordinates trades and inspections.
- Completion. Final sign-offs and handover.
Why choose us
- CSLB #1117595, class B general building contractor.
- One team from first sketch to final inspection.
- Office: 4000 MacArthur Blvd #600, Newport Beach.
- 5.0 on Google, 50 reviews. See our testimonials.
Huntington Beach ADU FAQ
Does Huntington Beach have a pre-approved ADU plan?
Yes. Under AB 1332 the City offers the HB Pre-Approved ADU Plan, a one-story detached ADU of 490 square feet. The City says modifications or deviations from the plan are not allowed.
Which ADU rules apply in Huntington Beach?
The City says its former ADU section, HBZSO Section 230.10, is no longer in effect, and state ADU and JADU law governs. The City reviews all ADUs and JADUs ministerially and publishes an ADU handout with development standards.
Will my ADU need a Coastal Development Permit?
It may, if the property is in the Coastal Zone. Under state law as summarized by HCD, the CDP for an ADU must be approved or denied within 60 days of a complete application.
What is a methane district, and does it affect my ADU?
The Fire Department maps methane districts in the city. Projects in these areas can need a separate fire permit, such as a Methane Barrier permit, filed through Accela Citizen Access.
How long does fire plan check take?
The Fire Department lists targets of 20 business days for the first review, 10 business days for a resubmittal and 5 business days after that.
What are construction hours in Huntington Beach?
With a valid permit, 7:00 a.m. to 7:00 p.m. Monday through Saturday. Construction is not allowed on Sundays or federal holidays.
Start with a feasibility call
Share your address and your goals for the unit, and we’ll tell you which route fits. Call (888) 599-7556 or contact us.