#1 ADU Contractor in Fountain Valley
Custom Builds by Horizon Remodeling
Horizon Construction & Remodeling Inc. builds accessory dwelling units and home additions for homeowners across Fountain Valley, handling design coordination, budgeting, permitting through the City of Fountain Valley Building Division, and material selection under one general contract. Many of the ranch-style tract homes built here in the 1960s and 1970s sit on lots with enough rear yard to support a detached unit or a garage conversion, though floodplain and seismic overlay districts can layer additional requirements on top of standard zoning rules. We coordinate every trade involved so the project meets applicable codes and works for your household.
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.
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If you are planning to add a secondary unit to your property, working with an experienced adu contractor in Fountain Valley means understanding a regulatory picture that layers state law, local zoning, and site-specific conditions all at once. California ADU law, codified in Government Code sections 66310 through 66342, was updated again on January 1, 2026. Square footage is now measured as interior livable space, and the approving agency has 15 business days to determine application completeness and 60 days to approve or deny. Approval is ministerial, meaning no hearing and no discretionary design review.
State law sets a floor of protections that apply regardless of where your parcel sits. A local agency cannot cap 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 units of 750 square feet or less.
Applications in Fountain Valley go through the City of Fountain Valley Building Division, and the city zoning map adds another layer worth knowing about. Floodplain and seismic hazard overlay districts cover portions of the city and stack additional requirements on top of the base zone, which can affect foundation design, grading, and structural details before a shovel touches the ground.
The lot itself drives most of the remaining decisions. Fountain Valley was largely built out during the 1960s and 1970s following incorporation in 1957, and the dominant housing stock is single-story or split-level ranch tract homes on slab foundations. That slab construction, combined with galley or L-shaped kitchens walled off from the living space, shapes where a detached unit can realistically sit, how far utilities need to run, and whether a garage conversion or a new detached structure is the more practical path. We walk every parcel and verify setbacks, grade, utility routes, and equipment access before a single line gets drawn.
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 Fountain Valley ?
Horizon Construction and Remodeling is a licensed and bonded Class B general building contractor, and we have been doing this work since 2009. Fountain Valley is a short drive from our Fullerton office, so this is a local job for us, not a long-distance one. A detached ADU is essentially a small house placed on a lot that already has a primary residence, covering foundation, framing, roof, envelope, plumbing, electrical service, a kitchen, and a bathroom.
Because Fountain Valley developed rapidly through the 1960s and 1970s, most lots here sit beneath a slab-foundation ranch or split-level tract home. Adding a detached ADU to that kind of property means working around existing drainage patterns and utility runs that were never planned with a second structure in mind. The City of Fountain Valley Building Division also layers floodplain and seismic hazard overlay requirements on top of base zoning, which can add review steps that a general remodel would not face.
Design-build matters here because the design decisions and the construction constraints are inseparable. One team draws the plans, coordinates permits through the Building Division, and completes the build, covering neighborhoods across the city including Green Valley, Tiburon, Southpark, and the Mile Square Park area.
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ADU Contractor Services in Fountain Valley
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ADU Contractor in Fountain Valley FAQ
What is an ADU and why should I build one?
An accessory dwelling unit is a secondary home on your existing property, built as a backyard cottage, a converted garage, or an in-law suite. Working with Horizon Construction and Remodeling on an ADU in Fountain Valley gives you a way to add rental income, house family members independently, or simply expand your living space.
How much does it cost to build an ADU in California?
What an ADU costs in Fountain Valley depends on details no contractor can assess from a description alone. The unit size and type matter, as does whether you are converting existing space or building a new detached structure on your slab-foundation lot. Utility runs, site conditions, and finish selections all move the number. What state law does spell out is where certain costs are capped. A unit with 750 square feet or less of livable interior space is exempt from impact fees. School fees only apply once a unit exceeds 500 square feet. Connection fees for a conversion or junior ADU are limited because the state does not classify those as a new residential use, and adding an ADU cannot force a fire sprinkler retrofit onto your existing home.
Anyone giving you a firm price before walking your property is working from assumptions, not facts. Because Fountain Valley’s zoning map includes floodplain and seismic hazard overlay districts, some lots carry requirements beyond the base zone, and those details only surface after we review the parcel and confirm setbacks and utility access with the City of Fountain Valley Building Division. We scope the project first, then give you a fixed price you can hold us to. One thing to state plainly: the CalHFA ADU grant program is closed and fully allocated. The agency itself warns that anyone offering to help you obtain that grant is running a scam.
Do I need permits for an ADU in Fountain Valley?
Yes, every ADU requires a building permit, though the approval process is ministerial rather than discretionary, meaning there is no hearing or design review board to face. State law sets firm deadlines: the reviewing agency has 15 business days to confirm the application is complete and 60 days to approve or deny it, and a pre-approved plan shortens that review window to 30 days. In Fountain Valley, applications go through the City of Fountain Valley Building Division, where floodplain and seismic hazard overlay districts can add requirements on top of the base zoning rules. Horizon prepares and submits the permit package and stays with the project through every inspection rather than passing that responsibility back to 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 Fountain Valley?
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. handles ADU design, permitting through the City of Fountain Valley Building Division, and construction as a single coordinated effort, managing the full process so your project meets building codes, stays within budget, and finishes on schedule.
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 & Remodeling Inc. to schedule a free consultation, where we assess your property, talk through your goals, and deliver a detailed estimate with design recommendations, then guide you through every phase of your ADU project from start to finish.
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.
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Horizon is a licensed Class B general building contractor serving Fountain Valley and the surrounding Orange County communities.
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