#1 ADU Contractor in Mission Viejo
Custom Builds by Horizon Remodeling
Horizon Construction & Remodeling Inc. builds accessory dwelling units and home additions for homeowners across Mission Viejo, handling design, budgeting, permitting, and material selection from the first conversation through final sign-off. Many of the city’s tract homes from the 1970s and 1980s sit on lots that accommodate a detached backyard unit or an attached addition, though projects here typically involve two layers of association review alongside the City of Mission Viejo Building Services division, and we coordinate with both as part of our process. Every project is built to current code.
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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 Mission Viejo means working with someone who understands both the state rules that govern ADU approvals and the local layers that apply specifically to this city. California ADU law, codified in Government Code sections 66310 through 66342 and updated as of January 1, 2026, measures square footage as interior livable space and gives local agencies 15 business days to determine whether an application is complete, then 60 days to approve or deny it. Approval is ministerial, meaning no hearing and no discretionary design review stands between you and a decision.
In Mission Viejo, that application goes to the Building Services division within the Community Development Department. Many of the homes here trace back to the Mission Viejo Company, which began delivering houses to the first Deane Homes families in 1966 and largely finished the city by 1980. Those 1970s and 1980s detached tract homes, typically Spanish mission style with stucco walls, barrel-tile roofs, and a kitchen that opens to a family room, shape every site decision, from where a detached unit can sit to how far utilities need to run.
If your home was built after 1978, mandatory Lake Mission Viejo Association membership adds a second layer of association rules on top of your tract association, both of which sit alongside city code. We review all three before drawing anything.
State law protects certain minimums regardless of parcel or association: a local agency cannot cap an ADU 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 fire sprinkler retrofit of the main house; and units of 750 square feet or less carry no impact fees. We walk the parcel first, check setbacks, grade, equipment access, and utility routes, and then we draw.
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 Mission Viejo ?
Horizon Construction and Remodeling is a licensed Class B general building contractor, bonded, with over 15 years of design-build work. A detached ADU is its own complete structure: foundation, framing, roof, electrical service, plumbing, a kitchen, and a bathroom, all placed on a lot where a primary home already stands. That scope touches multiple trades at once, which is exactly what a general building contractor is set up to coordinate.
Mission Viejo’s typical housing stock consists of 1970s and 1980s detached tract homes, and many of those lots have room for a backyard ADU. Permits run through the City of Mission Viejo Building Services division, and we prepare and manage that submittal as part of our standard process.
Homes built after 1978 here also carry Lake Mission Viejo Association membership on top of their individual tract association, meaning two layers of association rules sit alongside city code. We prepare association submittals alongside the building permit rather than treating them as an afterthought. Areas we regularly work in include Deane Homes, Casta del Sol, Madrid del Lago, and Canyon Estates.
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ADU Contractor Services in Mission Viejo
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ADU Contractor in Mission Viejo FAQ
What is an ADU and why should I build one?
An accessory dwelling unit is a secondary home on your existing lot, built as a backyard cottage, a garage conversion, or an in-law suite. Building an ADU in Mission Viejo lets you add rental income, house a family member independently, or simply gain more usable space on the generous lots common across 1970s and 1980s tract neighborhoods like Canyon Estates and Casta del Sol.
How much does it cost to build an ADU in California?
Pricing an ADU in Mission Viejo honestly depends on details no contractor can know from a distance: the size and type of unit, whether you are converting existing space or building a detached structure from the ground up, what utility runs your lot requires, and the finish level you choose. What we can tell you is how state law shapes the cost. A unit at or under 750 square feet of livable space is 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. Adding an ADU also cannot trigger a fire sprinkler retrofit requirement on your main house.
Beyond the City of Mission Viejo Building Services division review, many properties here carry two layers of association rules, a tract association and mandatory Lake Mission Viejo Association membership for homes built after 1978, and both sit alongside city code. That layering matters when scoping setbacks and exterior materials. Anyone quoting a firm number before walking the parcel is guessing. We visit the property, confirm the utility and setback situation, and deliver a fixed scope and price you can hold us to. One warning worth repeating: the CalHFA ADU grant program is closed and fully allocated, and the agency itself states that anyone offering to help you obtain that grant is running a scam.
Do I need permits for an ADU in Mission Viejo?
An ADU always requires a building permit, but the approval process is ministerial rather than discretionary, meaning no hearing and no design review board stands between your application and a decision. In Mission Viejo, that application goes to the Building Services division within the Community Development Department. State law gives the agency 15 business days to confirm completeness and 60 days to approve or deny, though a pre-approved plan shortens that review window to 30 days. Many of the tract homes in areas like Casta del Sol or Canyon Estates also carry association rules alongside city code, a layer we account for early. Horizon prepares and submits the full permit package and stays with the project through every inspection.
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 Mission Viejo?
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 Mission Viejo from design through final inspection, coordinating permits with the City of Mission Viejo Building Services division and keeping the work aligned with budget and schedule. Because many of these tract homes carry two layers of association rules, we factor HOA requirements in from the start.
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 your free consultation, where we assess your property, talk through your goals, offer design recommendations, and put together a detailed estimate covering every phase of your Mission Viejo ADU project.
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 Mission Viejo and the surrounding Orange County communities.
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