ADU Construction in Seal Beach, CA

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ADU Builder

ADU Construction in Seal Beach, CA

Serhal Builders builds ADUs in Seal Beach, including detached backyard units, garage conversions, attached ADUs and junior ADUs. Our office is in Fullerton, a short drive away.

About 89% of Seal Beach’s homes were built before 1980, and much of the city lies in California’s Coastal Zone, where an ADU can need coastal review in addition to the building permit. We check your parcel’s zoning, coastal status and any HOA rules before design.

We’re a licensed, veteran-owned general contractor (CSLB #1074208) with more than 31 years in construction, and we’ve built ADUs throughout northern Orange County.

Full-Service Solutions

Complete ADU Services in Seal Beach

One licensed contractor from design and permits to the final inspection.

Detached ADUs icon
Detached ADUs

A separate backyard home built from the ground up, with its own entrance, kitchen and bathroom.

Garage Conversions icon
Garage Conversions

We turn an existing garage into a full living space, often the most budget-friendly way to add a unit.

Attached ADUs icon
Attached ADUs

An addition connected to your home with its own entry, kitchen and bath, so family stays close but independent.

Junior ADUs (JADU) icon
Junior ADUs (JADU)

A unit of up to 500 square feet created inside your existing home, with its own entrance.

Design & Floor Plans icon
Design & Floor Plans

In-house design, plans from our design partner, or your own architect’s plans. We work whichever way suits you.

Permits & City Approval icon
Permits & City Approval

We prepare and submit the permit package and handle plan-check corrections with the city.

Utilities & Systems icon
Utilities & Systems

Electrical, plumbing, sewer, water and gas tie-ins planned early so there are no surprises mid-build.

Kitchens, Baths & Finishes icon
Kitchens, Baths & Finishes

Cabinets, counters, tile, flooring and fixtures, all handled by the same team that remodels full homes.

Why Choose Us

Solutions & Benefits

Every lot is different. These are the three ways most homeowners add a unit.

Detached ADU
Attached & JADU
Plans & Permits

Detached ADUs & Garage Conversions

A detached ADU gives you a separate backyard home with its own entry, kitchen and bath. A garage conversion reuses an existing structure and is often the most budget-friendly way to add a unit.

Attached ADUs & Junior ADUs

An attached ADU connects to your home but lives independently. A junior ADU is up to 500 square feet created inside your existing home, a good fit for family members who want their own space nearby.

Plans & Permits Your Way

Use our in-house design, our design partner, or plans you already have. We prepare the permit package, respond to plan-check comments and coordinate inspections until final sign-off.

Local Knowledge

What Seal Beach Homeowners Should Know

Coastal Zone – Projects in the Coastal Zone can need a coastal development permit or exemption, which adds a step before the building permit.
Older homes – Seal Beach's median home was built in 1966, and about 89% of homes predate 1980 (U.S. Census Bureau, ACS 2020–2024). We check the main panel, sewer line and water service early, because tie-ins on older homes can change the plan.
HOAs – California law doesn't let an HOA prohibit an ADU on a single-family lot, though it can set reasonable rules. We review those along with the city's.
Rules change – ADU laws are updated almost every year, so we confirm the current requirements with the city before design starts.
ADU floor plans for a Seal Beach home
Homeowners reviewing ADU floor plans
Simple Process

Our Working Process

Building an ADU in Seal Beach has more steps than a remodel. Our process keeps it clear and manageable.

We look at your lot, utilities and goals and recommend the ADU type that fits.
We design in-house, with our partner, or from your plans, then handle submittal and plan-check corrections with the city.
Our crew builds the ADU and coordinates every inspection through to final sign-off.
Quick Answers

Frequently Asked Questions

Are ADUs allowed in Seal Beach?

Yes. Seal Beach allows ADUs and junior ADUs under its local code and California ADU law. Your lot, utilities and any easements decide which type and size work best.

Does the Coastal Zone affect ADUs in Seal Beach?

It can. Much of Seal Beach is in the Coastal Zone, where an ADU may need a coastal development permit or exemption in addition to the building permit. We check your parcel first.

Can my HOA stop me from building an ADU?

California law doesn't let an HOA prohibit an ADU on a single-family lot, though it can set reasonable rules. We review your HOA's requirements along with the city's.

Are you a licensed contractor?
Yes. Serhal Builders is a licensed California general contractor (CSLB #1074208). We're veteran-owned and family-run, with more than 31 years of construction experience.
Do you handle the plans and permits?
Yes. We can design your ADU in-house, work with our design partner, or build from plans you already have. Either way we prepare the permit package and handle corrections with the city.
Can I convert my garage into an ADU?
In most cases, yes. California law generally does not allow cities to require replacement parking when a garage is converted into an ADU. We check your specific property before design.
How do I get started?
Call us at 949-829-4999 or request a quote online. We'll talk through your goals, look at your property and explain which ADU type fits best.