#1 ADU Contractor in Cowan Heights
Custom Builds by Horizon Remodeling
Horizon Construction & Remodeling Inc. builds accessory dwelling units on large hillside lots throughout Cowan Heights, handling design coordination, budgeting, material selection, and permitting from start to finish. Because Cowan Heights is unincorporated county territory, permits run through OC Development Services rather than a city building department, and the North Tustin Specific Plan governs land use here, so we factor those requirements in from the first consultation. The steep terrain and long private driveways common to these 1960s-era custom and split-level homes also shape how we plan site access and material staging.
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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Finding the right adu contractor in Cowan Heights starts with understanding that this community sits in unincorporated county territory, which means your permit application goes to OC Development Services rather than any city building department. State ADU law, updated as of January 1, 2026, measures square footage as interior livable space and gives the agency 15 business days to determine whether your application is complete, followed by 60 days to approve or deny it. Approval is ministerial, so there is no public hearing and no discretionary design review standing between you and a decision.
The North Tustin Specific Plan governs land use here, and the hillside terrain that defines Cowan Heights adds practical layers that a flat-lot project never faces. Long private driveways, steep grades, and the setback distances on large custom lots all shape what is buildable before a single line gets drawn. We walk every parcel first, checking grade, equipment access, utility routes, and setbacks so the design reflects what the land will actually support.
Most of the foothill housing here went in from the 1960s onward, developed gradually from the former Cowan Heights Ranch that Walter Cowan assembled in 1944 and later sold to homebuilders. The result is a stock of custom and semi-custom hillside houses, often single-story or split-level, sited for valley views, with closed-off kitchen layouts that influence where a detached unit can realistically sit and how far utilities need to run.
California law sets a floor that no local agency can undercut: an ADU cannot be capped below 850 square feet of interior livable space, or 1,000 square feet with more than one bedroom. Side and rear setbacks cannot exceed four feet, owner-occupancy cannot be required, building an ADU cannot trigger a sprinkler retrofit of the main house, and there are no impact fees on units at or under 750 square feet. The lot and these protections together decide most of what is possible.
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 Cowan Heights ?
Horizon Construction and Remodeling is a licensed and bonded Class B general building contractor, and we have been doing this work since 2009. Our Fullerton office puts Cowan Heights well within our regular working area, so your project gets the same attention we give a job around the corner. We also work in nearby Lemon Heights, Panorama Heights, Red Hill, and the broader North Tustin area.
A detached ADU is a complete small house built on a lot that already has a primary residence. That means foundation, framing, roof, exterior envelope, a kitchen, a bathroom, and the utility connections that make it livable. Because Cowan Heights is unincorporated county territory, permits go through OC Development Services rather than a city building department, and the North Tustin Specific Plan governs land use, so we prepare the application with that process in mind from the start.
The hillside lots that characterize this area, many of them large custom parcels developed from the 1960s onward, also shape how we plan staging and site access. We handle design, permitting, and construction under one roof, so the decisions made at the drawing stage hold through every inspection.
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ADU Contractor Services in Cowan Heights
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ADU Contractor in Cowan Heights 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 garage conversion, or an in-law suite. Adding one in Cowan Heights lets you generate rental income, house extended family, or gain extra living space on the large hillside lots that define this unincorporated North Tustin community.
How much does it cost to build an ADU in California?
What an ADU Actually Costs in Cowan Heights
No honest contractor can quote you a firm number from a web page alone, and that is especially true for the hillside lots throughout Cowan Heights and the wider North Tustin area. The final cost depends on whether you are converting existing space or building a detached unit from scratch, how much site work your parcel needs, and the finish level you choose. Long private driveways and sloped terrain affect both access and staging in ways that only a site visit can reveal. Because Cowan Heights is unincorporated county territory, permits run through OC Development Services, and the North Tustin Specific Plan governs land use here, so we confirm the full regulatory picture before we scope anything.
Once we walk the property, we give you a fixed scope and price you can hold us to. On costs the law does control: ADUs 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 a conversion or junior ADU are limited because the state does not classify those as a new residential use. A new ADU also cannot trigger a fire sprinkler retrofit of your existing home. One warning worth repeating: the CalHFA ADU grant program is closed and fully allocated, and the agency itself states that anyone offering to secure you an ADU grant is running a scam.
Do I need permits for an ADU in Cowan Heights?
Every ADU does require a building permit, but approval is ministerial rather than discretionary, meaning no hearing and no design review board stands between you and a decision. Because Cowan Heights is unincorporated county territory inside North Tustin, your application goes to OC Development Services rather than any city building department. State law gives the agency 15 business days to confirm completeness and 60 days to approve or deny, and a pre-approved plan shortens that review to 30 days. We prepare and submit the full package and carry it through every inspection, so you are not left managing the process on your own.
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 Cowan Heights?
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 in Cowan Heights from design through final inspection, coordinating permitting with OC Development Services and handling every trade involved, so your project meets building codes and stays on budget.
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?
Ready to move forward? Contact Horizon Construction & Remodeling Inc. to schedule a free estimate, and we will assess your Cowan Heights property, talk through your goals, and walk you through every phase of your ADU project from design to completion.
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 Cowan Heights and the surrounding Orange County communities.
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