#1 ADU Contractor in Seal Beach
Custom Builds by Horizon Remodeling
Horizon Construction & Remodeling Inc. builds accessory dwelling units throughout Seal Beach, handling design coordination, budgeting, permitting, and material selection so homeowners have one point of contact from the first conversation to the final walkthrough. Our work covers the full range of ADU types, from detached backyard cottages to attached additions, and every project is built to meet California Title 24 requirements and local code. Seal Beach permits go through the City of Seal Beach Building and Safety Division, and projects within Leisure World require Golden Rain Foundation approval and mutual sign-off in addition to city permits, a process we walk clients through carefully. Specialty trade portions are handled by appropriately licensed subcontractors we coordinate directly.
Services We Offer
How Our ADU Process Works
When it comes to enhancing your living space, room additions combined with Accessory Dwelling Unit (ADU) construction offer unparalleled versatility and value. These projects not only increase square footage but also provide additional living accommodations, whether for extended family, rental income, or work-from-home setups, making them a popular choice for homeowners seeking to maximize their property’s potential. According to California’s Department of Housing and Community Development, ADUs are a key solution to expanding housing options in urban and suburban neighborhoods.
Read More →
Working with an adu contractor in Seal Beach means navigating a permit process shaped by both state law and the city’s own building authority. Under California Government Code sections 66310 through 66342, as updated January 1, 2026, square footage is measured as interior livable space, and the reviewing agency has 15 business days to determine whether your application is complete, then 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.
For most Seal Beach addresses, that application goes to the Building and Safety Division within the Community Development Department. Leisure World is a different situation. Because residents there own shares in nonprofit mutuals rather than the land itself, a project requires Golden Rain Foundation approval and mutual sign-off alongside the standard city permit, which adds steps that need to be planned for from the start.
The housing history of Seal Beach directly shapes what is physically possible on a given parcel. Old Town was platted in the early 1900s on small original townsite lots, Surfside Colony followed in 1929, and the College Park neighborhoods were completed between 1964 and 1970. Those narrow Old Town lots handle setbacks and utility runs very differently than a College Park tract home. We walk every parcel before drawing anything.
State law sets a floor of protections that apply regardless of location. A local agency cannot restrict an ADU below 850 square feet of interior livable space, or 1,000 square feet for a unit with more than one bedroom. Side and rear setbacks cannot exceed four feet. Owner-occupancy cannot be required. Building an ADU cannot trigger a fire sprinkler retrofit of the main house. And there are no impact fees on a unit of 750 square feet or less.
Other Remodeling Services We Offer
A modern kitchen adds functionality, comfort, and lasting value to your home. At Horizon Construction & Remodeling, our kitchen remodeling experts bring fresh ideas and professional project management tailored to your unique needs. From layout design to material selection, we prioritize delivering a high-standard kitchen that’s both beautiful and energy-efficient — enhancing the way you cook, gather, and live every day.
Whether you envision a classic Southern California pool or a fully customized backyard oasis, Horizon Construction & Remodeling delivers the highest level of quality and service. Our comprehensive pool design and remodeling services cover everything from layout and decking to built-in BBQs and final touches like landscaping. Let Horizon be your trusted partner in transforming your backyard into the perfect outdoor retreat.
If you are planning a complete bathroom remodel or simply want to change your tub, shower, update your plumbing fixtures, or make the space more efficient, our team at Horizon will help you through the process with expert advice, professional craftsmanship, and affordable options with beautiful results. Learn more about our bathroom remodeling services.
Transform your space with our expert interior work services. We offer a comprehensive range of solutions — from space planning and custom design to the selection of high-quality finishes and materials. Our team of experienced professionals works closely with you to create a space that’s both functional and stylish, tailored to your unique needs, goals, and budget. Whether you’re updating a single room or overhauling your entire interior, we bring precision, creativity, and craftsmanship to every project.
At Horizon, we believe your home is more than just four walls — it’s where life happens. It’s the place you relax, gather with family and friends, and create lasting memories. That’s why we offer a full range of exterior work services designed to elevate your outdoor living space. From patios and hardscaping to custom decks and exterior renovations, we help turn your vision into a dream yard that complements your lifestyle and enhances curb appeal.
At Horizon Construction & Remodeling, our expert team includes a dedicated design and planning division that works hand-in-hand with licensed architects and structural engineers. We take care of everything — from detailed plans and blueprints to securing city permits — so you don’t have to deal with delays or red tape. Our goal is to streamline the process and provide a fully approved set of documents that aligns with both your vision and city regulations, saving you time and stress.
Why Choose Horizon Remodeling As Your ADU Contractor in Seal Beach ?
Horizon Construction and Remodeling is a licensed Class B general building contractor, bonded, and in business since 2009. Our office is at 614 S Euclid St in Fullerton, which puts Seal Beach well within our regular working area. We handle ADU projects across Old Town, College Park East, College Park West, and Leisure World.
A detached ADU is a full small house built on a lot that already has a primary residence. That means foundation, framing, roof, envelope, and a complete living unit with a kitchen and bathroom, with specialty trade portions coordinated through appropriately licensed subcontractors. Because design decisions and construction constraints are tied together from the start, having one team carry the project from drawings through the final inspection matters. Permits for ADU work in Seal Beach go through the City of Seal Beach Building and Safety Division within the Community Development Department.
Leisure World adds a layer most contractors overlook. Because residents own shares in nonprofit mutuals rather than the land itself, a project there requires Golden Rain Foundation approval and mutual sign-off alongside the city permit. We prepare both submittals together rather than treating the association review as an afterthought.
Schedule a Consultation
ADU Contractor Services in Seal Beach
View Our ADU Contractor Areas of Service
ADU Contractor in Seal Beach FAQ
What is an ADU and why should I build one?
An accessory dwelling unit is a self-contained secondary home on your existing property, taking the form of a backyard cottage, a converted garage, or an attached in-law suite. Adding one in Seal Beach can generate rental income, house extended family, or simply give your household more usable space, though homeowners in Leisure World should plan for Golden Rain Foundation and mutual approval alongside the standard City of Seal Beach permit process.
How much does it cost to build an ADU in California?
ADU costs in Seal Beach shift depending on factors no contractor can assess from a distance: the unit size, whether you are converting existing space or building a new detached structure, how much site and utility work your lot requires, and the finish level you select. What stays consistent is where the budget goes and what state law limits. Units at or under 750 square feet of livable space are exempt from impact fees, school fees apply only above 500 square feet, and connection fees for conversions and junior ADUs are capped because the state does not classify those as a new residential use. An ADU project also cannot force a fire sprinkler retrofit on your existing home.
Permit routing adds another layer in Seal Beach that homeowners should plan for early. City permits go through the Building and Safety Division inside the Community Development Department, but if your property sits within Leisure World, a Golden Rain Foundation permit and approval from the applicable mutual are required on top of the city filing. That approval process runs on its own timeline and affects scheduling. Any contractor quoting a firm price before walking your parcel and confirming setbacks, utilities, and any community-layer requirements is working from assumptions. We review the site first, then provide a fixed scope and price you can hold us to.
Do I need permits for an ADU in Seal Beach?
Building permits are required for every ADU, but approval in California is ministerial rather than discretionary, meaning there is no hearing and no design review board to satisfy. In Seal Beach, applications go to the Building and Safety Division within the Community Development Department, and state law sets firm deadlines: 15 business days to confirm completeness and 60 days to issue a decision, shortened to 30 days when a pre-approved plan is used. For properties inside Leisure World, a Golden Rain Foundation permit and mutual approval are also required on top of the city permit. Horizon prepares the full application package, submits it, and follows the project through every inspection so that responsibility never falls back on the homeowner.
How long does ADU construction take with Horizon Remodeling?
Most ADU construction projects take between 4 to 8 months from design to completion, depending on scope and permit approvals. Horizon Remodeling prioritizes efficient timelines while maintaining quality workmanship.
What types of ADUs can Horizon Remodeling build?
We specialize in building detached ADUs, attached ADUs, garage conversions, backyard cottages, and junior ADUs (JADUs). Our team can help you choose the right ADU style for your property and goals.
Can I build a detached ADU on my property in Seal Beach?
Yes, if your property meets California zoning and space requirements. Horizon Remodeling will assess your site, secure the necessary permits, and build a fully detached ADU tailored to your preferences.
Is Horizon Remodeling licensed to build ADUs in my area?
Yes, Horizon Remodeling is fully licensed, bonded, and insured to build ADUs throughout Orange County and surrounding areas. We have over 18 years of experience delivering high-quality ADU projects.
What are the benefits of hiring Horizon Remodeling for my ADU project?
Horizon Construction & Remodeling Inc. manages ADU projects from initial design through final inspection, coordinating permits with the City of Seal Beach Building and Safety Division and, for Leisure World properties, navigating Golden Rain Foundation and mutual approvals alongside the city process.
Does Horizon Remodeling handle ADU design and permitting?
Absolutely! Horizon Remodeling provides complete ADU design services, including architectural plans and 3D renderings. We also handle city permits and inspections, streamlining your project and reducing stress.
How do I get started on an ADU with Horizon Remodeling?
Reach out to Horizon Construction and Remodeling to schedule a free consultation, where we assess your property, talk through your goals, and deliver a detailed estimate covering every phase of your ADU project in Seal Beach, including any Golden Rain Foundation or mutual approvals required for Leisure World properties.
Recent ADU and Garage Conversions
Three completed ADU and garage conversion projects from our Orange County portfolio. Every project below was built in San Clemente. Nothing loads from YouTube until you press play.
ADU project in San Clemente
ADU project in San Clemente
ADU project in San Clemente
Built by Horizon Construction & Remodeling, Inc. Licensed Class B general building contractor.
Explore More in Seal Beach
Horizon is a licensed Class B general building contractor serving Seal Beach and the surrounding Orange County communities.
Other Services in Seal Beach
ADU Contractors Nearby
Related Posts About ADU
