#1 ADU Contractor in San Bernardino County
Custom Builds by Horizon Remodeling
Horizon Construction & Remodeling Inc. builds accessory dwelling units throughout San Bernardino County, handling design coordination, permitting, material selection, and construction management so you have one point of contact from the first conversation to the final walkthrough. The goal is straightforward: add usable square footage to your property without the headaches that come from juggling multiple contractors on your own.
San Bernardino County covers an unusually wide range of housing stock, and that variety shapes how every ADU project starts. The valley cities like Ontario, Rancho Cucamonga, Fontana, and Chino Hills are largely 1970s through 2000s tract homes sitting on generous lots, many with pools and enough rear yard to accommodate a detached unit comfortably. Mountain communities like Big Bear and Lake Arrowhead, along with the high desert areas around Victorville and Hesperia, bring a different set of conditions, including snow-load structural requirements and Wildland Urban Interface fire rules that affect materials and framing choices. Summer heat across the valley also pushes us to pay close attention to insulation, ventilation, and cooling from the design stage forward.
Permits for ADU construction in San Bernardino County depend on where your property sits. Incorporated cities including San Bernardino, Rancho Cucamonga, Ontario, Fontana, and Chino Hills each issue their own building permits, while unincorporated areas, mountain communities, and the high desert fall under San Bernardino County Land Use Services. We identify the correct jurisdiction early and handle the permit application and inspection coordination as part of our standard process, because mixing those up costs time and money.
Specialty trade portions of every ADU project, including electrical, plumbing, and HVAC work, are performed by appropriately licensed subcontractors we coordinate directly. As a licensed and bonded general contractor, we manage that coordination so the work moves in the right order and every trade is on-site when the schedule calls for it. The result is a finished unit built to current code that functions as a genuine addition to your home, not an afterthought.
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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San Bernardino County updated its ADU rules through Development Code Chapter 84.36, adopted by the Board of Supervisors on January 13, 2026, making it the most current county ADU ordinance among the four counties we serve. Under those published standards, a standard ADU can range from 200 to 1,200 square feet, and a junior ADU tops out at 500 square feet. Attached structures are permitted up to 25 feet in height, detached up to 18 feet with two additional feet available to match an existing roof pitch. Side and rear setbacks land at four feet, with five feet of required separation between detached structures.
Two provisions set this county apart from the coastal counties we work in. First, the county allows two ADUs per lot, and properties of five acres or more can carry three units total. Second, sewer connection is required when a sewer main runs within 200 feet of the property line, and that distance grows by 100 feet for each additional dwelling unit added. Projects outside that range rely on septic or an advanced treatment system, and the county requires a percolation test no older than five years, or ten years if it has been formally recertified.
That sewer and septic question determines whether a project is feasible before a single plan is drawn, so we bring in the Environmental Health division early in the process rather than discovering a problem after design work is complete. This matters especially on desert and mountain parcels around areas like Victorville, Hesperia, Big Bear, and Lake Arrowhead, where lot conditions and utility access vary considerably from the valley cities. Mountain and hillside sites also carry snow-load structural requirements and Wildland Urban Interface fire rules that affect material choices and framing, and we account for those during the design phase rather than at permit review.
For permitting, Building and Safety under Land Use Services handles the unincorporated county, while the 24 incorporated cities each issue their own permits. Cities like Rancho Cucamonga, Ontario, Fontana, and Chino Hills run their own review processes, and the county publishes pre-approved detached ADU plan sets that qualify for the shorter 30-day review track. On the valley floor, where the typical single-family tract home sits on a generous lot, often with a pool and extra yard space, those pre-approved plans can move a straightforward detached ADU through the system faster than a fully custom set of drawings.
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 San Bernardino County ?
Horizon Construction & Remodeling builds ADUs throughout San Bernardino County as a licensed Class B general building contractor, bonded, and with more than 15 years of design-build experience behind us.
In San Bernardino County, the right questions to ask before design begins are about feasibility: sewer or septic service, percolation, well access, fire hazard zone classification, and which of the county’s three distinct regions the parcel sits in. Those answers shape everything that follows. Permits flow through different agencies depending on location, so a lot in Rancho Cucamonga or Ontario goes through that city’s building department, while a parcel in Big Bear, Lake Arrowhead, or the high desert around Victorville typically falls under San Bernardino County Land Use Services for unincorporated areas. We sort that out at the start so nothing stalls mid-project.
A 1,200 square foot ADU on a generous valley-floor lot in Fontana or Chino Hills is a fundamentally different build from the same unit on a mountain or high desert site. Summer heat in the Inland Valley drives real demand for proper insulation and cooling capacity, while mountain and hillside communities in Big Bear and Lake Arrowhead carry snow-load requirements, frost-depth considerations, freeze protection for plumbing, and Wildland Urban Interface fire rules that affect materials and design at every level. Structure, mechanical systems, and finish details all shift depending on which part of the county the project sits in.
California state law provides certain protections that follow the parcel regardless of location. There is no owner-occupancy requirement attached to building an ADU. Constructing an ADU does not trigger a sprinkler retrofit of the existing main house. And for any unit with 750 square feet or less of interior livable space, no impact fees apply. These protections hold across the valley, the mountains, and the high desert.
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ADU Contractor Services in San Bernardino County
ADU cities we serve in San Bernardino County
ADU Contractor in San Bernardino County FAQ
What is an ADU and why should I build one?
A secondary housing unit built on your existing property goes by several names: backyard cottage, garage conversion, in-law suite, or simply an ADU. San Bernardino County ADU construction gives homeowners a practical way to add rental income, house extended family, or gain usable living space without buying a new property. Horizon Construction & Remodeling Inc. coordinates the entire process, from design through final inspection, so the finished unit works for your household and your lot.
The county’s housing stock shapes what each project looks like on the ground. The 1970s through 2000s tract homes that fill the valley cities of Ontario, Rancho Cucamonga, Fontana, and Chino Hills typically sit on generous lots, often with a pool and enough rear yard to accommodate a detached ADU or a garage conversion without crowding the property. Mountain communities like Big Bear and Lake Arrowhead, along with the high desert areas around Victorville and Hesperia, bring a different set of conditions: Wildland Urban Interface fire rules affect exterior material choices, snow-load requirements apply to roof framing, and those factors get built into the structural design from the start, not added as an afterthought.
How much does it cost to build an ADU in California?
ADU construction costs in San Bernardino County vary based on factors no contractor can pin down from a website alone: the size and type of unit, whether you are converting existing space or building a new detached structure, how much site work and utility extension your lot requires, and the finish level you select. What we can explain is where the budget goes and what state law limits.
A unit with 750 square feet or less of interior livable space is exempt from impact fees. School fees apply only when the unit exceeds 500 square feet. Connection fees for a conversion or junior ADU are capped under state law, because those unit types are not treated as a new residential use for fee purposes. Adding an ADU to your property also cannot force a fire sprinkler retrofit on your existing home.
Tract homes on the generous lots common across the Inland Valley cities tend to have enough rear yard space to accommodate a detached ADU without major site complications, but every parcel is different. Mountain and high desert properties covered by San Bernardino County Land Use Services rather than a city building department face additional considerations, including snow-load requirements and Wildland Urban Interface fire rules that affect materials and construction methods, so the site review is especially important in those communities.
Any contractor quoting a firm number before walking your property is estimating without enough information. We visit the site, verify setbacks, confirm the utility situation, and then give you a defined scope with a price you can hold us to.
One fact worth stating clearly: the CalHFA ADU grant program is closed and its funding has been fully allocated. The agency itself has warned that anyone offering to help you obtain an ADU grant is operating a scam.
Do I need permits for an ADU in San Bernardino County?
Yes, every ADU requires a building permit before construction begins. If your property sits in an unincorporated part of San Bernardino County, including mountain communities like Big Bear and Lake Arrowhead or high desert areas around Victorville and Hesperia, your application goes to San Bernardino County Land Use Services, Building and Safety rather than a city building department. County guidance already incorporates the state-mandated review windows: 15 business days for a completeness determination and 60 days to approve or deny the application. Incorporated cities such as Rancho Cucamonga, Ontario, Fontana and Chino Hills each run their own permit offices, so the submittal destination depends on which jurisdiction your lot falls under.
Because many of the larger valley lots throughout the county rely on septic systems or private wells, Environmental Health typically joins the review process on those properties. The sewer proximity rule also applies: if a public sewer line runs within 200 feet of your property line, connection is required. Horizon coordinates the full submittal package, works through any correction notices, and schedules each required inspection so the permit process moves forward without putting that burden on you.
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 San Bernardino County?
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 projects across San Bernardino County from the first design conversation through the final inspection. We coordinate every phase in-house, working directly with whichever jurisdiction issues your permit, whether that is the City of Rancho Cucamonga, Ontario, Fontana, Chino Hills, or San Bernardino County Land Use Services for unincorporated areas, mountain communities like Big Bear and Lake Arrowhead, and the high desert cities around Victorville and Hesperia. The goal is a finished unit that satisfies local code, fits your budget, and does not drag on longer than it needs to.
San Bernardino County’s housing stock shapes how we approach each job. The generous lots common on 1970s through 2000s tract homes in the valley cities often have room for a detached ADU alongside an existing pool or garage, while mountain and hillside parcels bring their own requirements, including snow-load engineering and Wildland Urban Interface fire-resistant material rules. Summer heat across the valley also factors into our planning, so we pay close attention to insulation specifications and cooling performance to keep the finished unit comfortable and compliant with California’s Title 24 energy standards.
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?
Contact Horizon Remodeling to schedule a free consultation. We’ll assess your property, discuss your goals, provide design recommendations, and deliver a detailed estimate. From there, our team guides you step-by-step through every phase of your ADU project.
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