A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across Chino Hills
A home addition in Chino Hills typically costs between $180 and $420 per square foot, with most full-scope projects landing between $120,000 and $380,000 depending on size, slope, and finish level. We’re Benson ADU Builders, led by Troy Eastman, and our Home Addition Contractor team handles everything from a 200-square-foot bump-out to a full second-story addition. If you’re planning to add square footage anywhere in Chino Hills, call (903) 568-7222 and we’ll give you a written price before any work starts.
Chino Hills isn’t a flat, easy build site. It’s a community of rolling hills, ridgeline lots, and neighborhoods carved into slopes that most cities never have to engineer around. That changes how foundations get designed, how drainage gets handled, and how long permit review takes. We plan for that from day one, which is why homeowners from Butterfield Ranch to Summit Ranch keep our number saved.
Why Benson ADU Builders Is Chino Hills’s Preferred Home Addition Contractor Company
Homeowners in Chino Hills tell us the same thing: they got a verbal estimate from another contractor, then watched the number climb once the geotech report came back. We don’t work that way. Every project starts with a written price, a defined scope, and a realistic calendar that accounts for the city’s hillside grading and drainage review. If we flag something that could change the price, you hear it before you sign, not after demo starts.
Our crews run background-checked and in uniform, and a live person answers the phone around the clock. When you’re spending six figures on an addition, you should know exactly who’s walking onto your property and exactly what they’re doing that day. Troy Eastman sets that standard on every Chino Hills project we run.
We’re part of the Relay Home Co. family, founded in 2006, and every project carries the 365-Day Done Right Promise. If the work isn’t right within a full year, we make it right. That’s in writing, stamped on your project file, along with a free second visit if any covered repair fails. Dispatch for Chino Hills jobs is coordinated from our Inland Empire office, so scheduling doesn’t depend on a single person’s calendar.
Garage Addition Contractors in Chino Hills
Garage Addition Contractors in Chino Hills handle two very different jobs: adding a new garage bay or converting part of an existing garage into conditioned living space while keeping the rest as storage. Most Chino Hills homeowners choose this route when they need a workshop, a home gym, or a secondary living area without pushing their footprint into the rear setback. On a typical flat-lot garage addition, expect to budget $65,000 to $140,000 depending on whether you’re adding a bay or finishing out existing space. Hillside lots add foundation and drainage scope, which can push that range 20 to 35 percent higher.
Sloped Lots and Garage Foundations
If your Chino Hills lot has any meaningful grade change, the garage addition is no longer a simple slab pour. The city’s hillside standards require geotechnical review, which often means over-excavation, deeper footings, or a retaining element before the walls go up. We scope that on the front end so the written price you get is the price you build to.
Matching the Existing House
Chino Hills has a lot of 1980s and 1990s construction with specific rooflines and stucco or siding profiles. A garage addition that doesn’t match pulls down the whole street presence, which matters when you eventually sell. We use James Hardie siding and trim to match existing profiles and bring the roofline in line with the main house, so the addition reads as original rather than tacked on.
Bathroom Addition Contractor in Chino Hills
A Bathroom Addition Contractor in Chino Hills is usually adding a full bath to a home that was built with too few for its current household size. That could mean a primary-suite bath above a garage, a guest bath off a family room, or a hallway bath that makes a three-bedroom house livable as a four-bedroom. A standard 5-by-8 to 8-by-10 bathroom addition in Chino Hills runs $45,000 to $85,000, depending on whether it shares a wall with existing plumbing or requires new drain lines. If you’re adding a bath as part of a primary suite, budget $100,000 to $160,000 for the combined scope.
Plumbing Runs and Slab Work
Chino Hills homes built in the 1970s through 1990s often have cast-iron drain lines under the slab. Tying a new bathroom into those lines means cutting concrete, and sometimes replacing a section of old pipe. We inspect the existing system before we quote so you’re not surprised by a cracked line once the saw starts.
Wet Wall Planning
The cheapest bathroom addition is the one that shares a wet wall with an existing bath or laundry. The most expensive is the one that needs a new vent stack through the roof and a drain run across the house. We’ll show you both options on paper, with dollar figures next to each, before you commit.
Trusted Brands We Service in Chino Hills
We don’t ask Chino Hills homeowners to take our word on materials. We build with brands you can research independently, including Abodu, Cover, and Dvele for prefab panel systems, plus James Hardie cladding for exterior finish work. If you’re doing a room addition or a second-story addition, prefab panels can cut framing time significantly compared to fully site-built work, which is useful when your lot’s hillside permit review already added weeks to the front end. We keep a running inventory of James Hardie siding profiles in stock for Chino Hills jobs, so matching your existing exterior doesn’t mean waiting on a special order.
Common Home Addition Contractor Problems We See in Chino Hills Homes
- Flat-lot assumptions on sloping lots. A contractor who quotes Chino Hills work using flat-lot footings will come back with change orders the moment the geotech report lands. We price hillside foundations from the start because we know the city requires geotechnical and drainage review on most slope-adjacent additions.
- Treating the addition like a simple remodel. Chino Hills has a hillside overlay that can trigger separate grading and drainage permits before framing begins. Skipping that step delays the whole job and can get the project flagged at rough inspection.
- Setback and height surprises. The lot’s slope band determines how close you can build to the property line and how tall the new roofline can go. A plan that ignores those limits gets rejected at the city counter, and you’ve already paid the design fee.
- Drainage afterthoughts. Adding square footage changes where rainwater goes. On a Chino Hills hillside lot, a poorly planned downspout or swale sends runoff toward the neighbor’s foundation or back into your own. We design drainage as part of the addition, not as a fix after the first winter storm.
Pricing for Home Addition Contractor in Chino Hills, CA
Here’s the honest math for Chino Hills. A basic room addition without plumbing runs $55,000 to $95,000. A bathroom addition runs $45,000 to $85,000. A garage addition runs $65,000 to $140,000. A full primary-suite addition runs $120,000 to $220,000. A second-story addition over an existing footprint runs $180 to $320 per square foot. The biggest variables in Chino Hills are slope, soil condition, and whether your existing plumbing and electrical panels need upgrading to carry the new load. A written estimate from us includes all of that – no verbal range that shifts at the door. Call (903) 568-7222 to schedule your free estimate, and we’ll walk the property with you before we put any number on paper.
In the Summit Ranch neighborhood above Grand Avenue, our crew built a primary-suite addition over a graded slope where the original soil report flagged expansive clay. We had to over-excavate and install a deeper footing system than the homeowner initially expected. We used James Hardie siding to match the existing stucco and brought the roofline in line with the main house. The project passed final inspection after geotech and drainage sign-offs, and the added square footage is now reflected on the county assessor’s record.
We Also Serve Cities Near Chino Hills
Our crews run additions in Pomona, Diamond Bar, Chino, and Montclair as well. If you’re on the western edge of Chino Hills near the 71 or up in the Butterfield Ranch area, our scheduling team routes from the Inland Empire office to keep drive times short and arrival windows reliable. See more about our work at Home Addition Contractor in Chino Hills.
Serving Chino Hills, CA - Our Local Coverage Area
We’re based in the Chino Hills area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Home Addition Contractor in Chino Hills
Yes, most additions on Chino Hills hillside lots require a geotechnical report before the city issues a building permit. The report tells the structural engineer what kind of soil the foundation sits on and whether it has expansive clay or fill material that needs mitigation. If your lot has a slope over a certain threshold, the city will not accept plans without it. Call (903) 568-7222 if you already have a soil report and want us to review what it means for your budget.
Design and permit review for a Chino Hills addition typically takes 3 to 5 months, and construction runs 3 to 6 months depending on scope. Hillside lots add time during plan check because the city’s grading and drainage review runs parallel to standard building review. A flat-lot bump-out moves faster than a second-story addition on a slope. We give you a written schedule with the estimate so you know which weeks are design, which are inspection, and which are construction.
Slope, soil, and existing utility capacity drive cost more than anything else in Chino Hills. Deeper footings on expansive clay, drainage swales required by the hillside overlay, and a panel upgrade to carry the new electrical load all add real money. Finish level matters too, but not as much as the ground under the slab. We break all of this out line-item in your written price.
Yes, we build garage additions and bathroom additions on Chino Hills hillside lots all the time, but the foundation and drainage scope is different from a flat lot in Chino or Ontario. Expect geotechnical review, possibly a retaining wall, and extra time in plan check. We price that reality into the estimate from day one instead of discovering it mid-project. The free estimate covers the site walk and the written scope, so call (903) 568-7222 to get started.
Very little, if the initial survey and geotech report were done correctly. The honest answer is that hidden conditions like an undocumented septic line, a failing section of cast-iron drain, or soil worse than the report suggested can trigger a change order, but those are rare when we’ve done our site work first. Your written price from Benson ADU Builders includes the hillside scope up front, and we document any change in writing with a new signature before we proceed. That’s the whole point of our no-hassle upfront pricing.
Key Takeaways for Chino Hills Homeowners:
- Budget $180 to $420 per square foot, with hillside lots at the higher end.
- Expect geotechnical and drainage review before your building permit is issued.
- Get a written price that accounts for slope, soil, and utility upgrades before work starts.
- Garage additions run $65,000 to $140,000; bathroom additions run $45,000 to $85,000.
- Every project carries a 365-Day Done Right Promise and a written guarantee.
Planning an addition anywhere in Chino Hills, from the 91709 zip near the 71 to the neighborhoods east of Chino Hills Parkway? Call (903) 568-7222 today. We’ll walk your lot, explain what the hillside rules mean for your specific project, and hand you a written price you can actually build to.
Written by Troy Eastman, Owner at Benson ADU Builders, serving Chino Hills homeowners with written pricing and the 365-Day Done Right Promise on every project.
