Design Center & Showroom · 614 S Euclid St, Fullerton · Mon–Fri 9am–5pm

#1 ADU Contractor in Corona
Custom Builds by Horizon Remodeling

Horizon Construction & Remodeling Inc. builds accessory dwelling units and home additions throughout Corona, managing design, budgeting, permits, and material selection from start to finish. Corona’s rapid suburban growth since the 1980s left the city with a wide range of properties, from newer two-story tract homes in foothill subdivisions to early twentieth century bungalows near the Grand Boulevard circle, where the City of Corona Building Division may require an additional layer of historic review before work can begin. Every project is handled to meet applicable city codes and your goals.

Services We Offer

Room Additions​

Sunroom Additions​

Garages & Conversions​

Extensions​

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.

If you are planning to add a secondary unit to your property, working with an experienced adu contractor in Corona means understanding how state law and local rules interact before a shovel touches the ground. California consolidated its ADU statutes into Government Code sections 66310 through 66342 in 2024, and those rules changed again on January 1, 2026. Square footage is now measured as interior livable space rather than overall footprint, and once you submit your application the reviewing agency has 15 business days to determine whether it is complete and 60 days to approve or deny it. Approval is ministerial, meaning no public hearing and no discretionary design review.

For any property in Corona, that application goes to the City of Corona Building Division. One detail that catches some homeowners off guard is the historic resources chapter in Corona’s municipal code. Properties listed on the Corona Register of Historic Resources or the Corona Heritage Inventory can face an additional layer of review, and homes near the Grand Boulevard circle, where early twentieth century bungalows are common, are the most likely candidates. If your property falls into that category, we factor that review into the schedule from the start.

Corona grew rapidly from roughly 76,000 residents in 1980 to 157,136 in 2020, and most of that growth produced two-story tract homes in foothill subdivisions with open floor plans and center islands. That housing profile matters because lot configuration and utility placement vary considerably across different parts of the city, and those variables shape where a detached unit can realistically sit and how far water, sewer, and electrical connections have to run.

Riverside County operates a Permit Ready ADU program offering four pre-approved plans ranging from a 499 square foot studio to a 909 square foot two-bedroom unit. Three of those plans fall under 750 square feet, which places them below the state impact fee threshold. The program does exclude parcels in flood hazard or environmental constraint areas, so confirming which maps apply to your lot is one of the first things we check. State law preempts any county provisions that are more restrictive than what Sacramento allows, including older height caps and parking requirements that appeared in earlier county handouts.

A homeowner reading outdated county materials might conclude they can build less than current law actually permits. Part of what we do is cut through that confusion, verify what your specific parcel allows, and coordinate the full scope of the project, including any specialty trade work performed by appropriately licensed subcontractors. Contact us to request a free estimate and get a clear picture of what your Corona property can support.

Other Remodeling Services We Offer

Why Choose Horizon Remodeling As Your ADU Contractor in Corona ?

ADU Contractor in Corona

Horizon Construction and Remodeling is a licensed Class B general building contractor, bonded, and in business since 2009. We handle ADU projects in Corona from the initial drawing through the final inspection, with one team managing the plan, the permit submittal to the City of Corona Building Division, and the construction itself. Coordinating all of that under one contract keeps the project moving and reduces the back-and-forth that slows so many ADU builds down.

Corona grew rapidly from an agricultural area into a largely suburban city, which means most parcels are tract homes built after 1980 with yards that can accommodate a detached or attached ADU under current state law. Homes near the Grand Boulevard circle are a different situation. That older core includes early twentieth century bungalows that may appear on the Corona Register of Historic Resources or the Corona Heritage Inventory, and work on those properties can trigger an additional layer of review beyond the standard permit process.

Regardless of where your property sits, certain state protections apply. There is no owner-occupancy requirement for an ADU, no sprinkler retrofit required on the main house, and no impact fees on a unit with 750 square feet or less of interior livable space. We work across Corona, including South Corona, Eagle Glen, and Dos Lagos. Contact us to request a free estimate.

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ADU Contractor Services in Corona

ADU Contractor in Corona FAQ

What is an ADU and why should I build one?

An accessory dwelling unit is a secondary home built on your existing lot, taking the form of a converted garage, a backyard cottage, or an in-law suite attached to the main structure. Building an ADU in Corona gives you rental income potential, added space for family, or both, and permits run through the City of Corona Building Division.

What an ADU Actually Costs in Corona

Any contractor who quotes you a firm number before walking your lot is guessing. The real cost depends on factors that vary from parcel to parcel: the size and type of unit you want, whether you are converting an existing space or building a detached structure from scratch, how far utility lines need to run, and the finish level you select. Corona’s rapid suburban growth means most properties are tract homes built after the 1980s on relatively standard footprint lots, but site conditions still differ enough that a walkthrough is the only honest way to build a real scope. Older homes near the Grand Boulevard circle may also face additional review under the city’s historic resources chapter before the City of Corona Building Division issues permits, which can affect both timeline and cost.

State law does give you some cost protections worth knowing. An ADU 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 treat those as a new residential use. Adding an ADU also cannot force a fire sprinkler retrofit on your existing house. One firm warning: the CalHFA ADU grant program is closed, its funds fully allocated, and the agency itself states that anyone offering to help you obtain an ADU grant is running a scam. We walk your property, confirm setbacks and utility conditions, and then give you a fixed scope and price you can hold us to.

Yes, an ADU in Corona always requires a building permit, though approval is ministerial rather than discretionary, meaning there is no hearing and no design review board to satisfy. Applications go to the City of Corona Building Division, which has 15 business days to confirm completeness and 60 days to approve or deny the permit, though a pre-approved plan can shorten that review to 30 days. We prepare and submit the full package and carry the project through every inspection, so the process never lands back on the homeowner.

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.

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.

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.

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.

Horizon Construction & Remodeling Inc. manages ADU projects in Corona from design through the City of Corona Building Division permit process to final construction, coordinating every trade so the finished unit meets code and fits your budget. Homes near the Grand Boulevard circle may require additional historic review before work begins.

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.

Reach out to Horizon Construction & Remodeling Inc. to schedule a free consultation, where we assess your property, talk through your goals, offer design recommendations, and put together a detailed estimate before guiding you through every phase of your Corona ADU project.