Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Mentone
A home addition or ADU in Mentone typically runs $45,000 to $130,000 for an addition and $90,000 to $220,000 for a detached ADU, and the county’s Chapter 7A fire-safety rules will shape almost every permit you pull. That’s the number you need first. The second thing you need is a contractor who already knows Mentone’s unincorporated county rules, expansive soils, and tight-lot staging challenges before the first truck shows up. Barrett & Sons Construction has built additions and ADUs throughout Mentone for years, and we answer our own phone. Call (877) 610-1318 for a free estimate from Tom Barrett’s crew, not a call center.
Key Takeaways for Your Mentone Addition or ADU
- Every permit-triggered project in Mentone must meet California Building Code Chapter 7A fire-resistant standards because the community sits in a Very High Fire Hazard Severity Zone.
- Mentone’s alluvial-fan soils are expansive and poorly consolidated, so an engineered soils report is often required before footings are poured.
- A garage conversion ADU in Mentone runs $30,000 to $80,000, while a new detached ADU starts around $90,000 and goes up with site work, utilities, and fire-hardening upgrades.
- County inspectors will flag non-compliant attic and crawl-space vents on older Mentone ranch homes, which can add scope and cost to a project that starts as a simple room addition.
- We stage materials and equipment on tight Mentone lots without blocking neighbors or the street. That’s part of the quote, not an afterthought.
Why Barrett & Sons Construction Is Mentone’s Preferred Home Additions & ADU Company
Tom Barrett founded Barrett & Sons Construction in 1998, and his sons run the crews that work in Mentone. Tom’s name, address, and license number are published and verifiable. Ask anyone on your street, or look it up yourself before you sign anything. That’s how every job here starts.
Mentone homeowners tell us the same thing: a national company quoted one price over the phone, then handed them a different bill at the door. We don’t work that way. Every scope change on a Mentone addition or ADU arrives as a written change order before a single nail moves. The allowance that isn’t on paper is a surprise waiting for a date.
Our crews know the difference between county and city building rules here. Mentone is unincorporated San Bernardino County, not Redlands. That changes work-hour ordinances, permit routing, and fire-safety inspections. We pull permits and get inspections signed on every eligible job, and the 90-Day Done Right Promise is written on the contract. If something isn’t right, Tom comes back. One call.
Our Home Additions & ADU Services in Mentone
ADU Design & Permitting
An ADU in Mentone starts with two questions: what will the county allow on your lot, and what will Chapter 7A force you to upgrade on the existing house. We walk both paths before you spend a dollar on plans. Our Home Additions & ADU team handles the drawings, the soils report, the county submittal, and the inspection schedule, so you deal with one crew instead of four vendors.
Many Mentone ADUs are designed as detached units over existing garages or as new builds on larger lots near the old citrus-era parcels. We design for the lot you actually have, not a catalog.
Garage Conversion ADU
Converting a garage in Mentone runs $30,000 to $80,000 depending on the structural condition of the slab and walls, the electrical service, and whether the existing vents meet Chapter 7A. Homes built in the 1950s and 1960s along Mentone Boulevard and nearby streets often have original unrated attic and crawl-space vents. The county inspector will flag those. We budget for them up front so the quote is honest.
On a tight Mentone lot, a garage conversion makes sense because you’re building inside an existing footprint. No new setback fights, less site work, and the county still treats it as a separate dwelling unit with its own address and meter.
New Detached ADU
A new detached ADU on a Mentone lot runs $90,000 to $220,000. The spread comes from site conditions. Where the lot sits on the alluvial fan, whether the soil report calls for deeper footings or a mat foundation, and how far utilities have to run from the main house all move the number. We give you a written line-item quote after the site walk, not a range that drifts.
If your lot is in the wildland-urban interface zone near the foothills, expect ignition-resistant siding, ember-resistant vents, and Class A roofing as base requirements. We quote those as standard, not as an extra surprise mid-job.
Junior ADU & Interior Conversion
A junior ADU carved out of an existing bedroom or attached space can be the fastest and least expensive way to add a legal unit in Mentone. Costs often track below a full detached ADU because the structure already exists. What still matters: a separate entrance, a kitchenette, and county sign-off on the conversion. We handle all three.
Some Mentone homes have large laundry rooms or bonus rooms that convert well. We’ll tell you honestly if yours doesn’t. Not every interior space makes a legal JADU, and we won’t sell you one the county won’t approve.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Mentone
We build additions and ADUs with materials you can look up. For patios and walkways that tie an ADU into the landscape, we install Belgard and Techo-Bloc pavers because they hold up to Mentone’s Santa Ana wind season and high summer heat without fading or shifting. For exterior assemblies on new additions, we spec ignition-resistant siding and Class A roofing assemblies from manufacturers with published fire-test data. You’ll see the brand names on the quote, not a mystery material off a van. Call (877) 610-1318 and we’ll walk you through the options for your specific Mentone lot.
Common Home Additions & ADU Problems We See in Mentone Homes
- Slab cracks from skipped soils reports. Mentone sits on debris-flow alluvial fan deposits that are expansive and poorly consolidated. We’ve seen additions on nearby parcels with slab cracks within a few years because the original contractor skipped the engineered soils report. We don’t skip it.
- Chapter 7A vent failures on older ranch homes. A 1960s Mentone ranch often has original unrated attic vents that look fine but don’t meet current ember-intrusion rules. Any permit-triggered addition forces replacement. We catch that in the estimate, not in change order number three.
- Staging headaches on tight lots. Many Mentone lots are narrow, with shared driveways or alley access. If your contractor can’t stage materials without blocking a neighbor, the job stalls. We plan access and parking before we quote so the number reflects the real site.
- Crews that assume city rules apply. Mentone is unincorporated county land. Work-hour and noise ordinances are county rules, not Redlands codes. A contractor who schedules city-style hours here risks neighbor complaints and a stop-work notice from the county.
Pricing for Home Additions & ADU in Mentone, CA
Here’s what Mentone homeowners can expect, in real numbers.
| Project Type | Typical Mentone Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
What moves these numbers in Mentone: the engineered soils report, Chapter 7A fire-hardening upgrades on the existing house, utility runs across larger lots, and site access for staging. A simple room addition on a flat lot with modern vents comes in at the low end. A detached ADU on a hillside parcel with poor access and an old electrical panel lands higher. Every quote we give is a written line-item estimate. Every change after that is a signed change order before work continues. Call (877) 610-1318 for a free estimate, and we’ll give you a number you can take to your lender, not a range that drifts later.
We Also Serve Cities Near Mentone
From our Inland Empire office we send crews to Mentone and the surrounding communities every week. If you’re in Mentone or just outside it in Redlands, Yucaipa, Highland, or Calimesa, the same crew and the same written-price rules apply. Call (877) 610-1318 and tell us which side of the county line your lot sits on.
Serving Mentone, CA - Our Local Coverage Area
We’re based in the Mentone 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 - Home Additions & ADU in Mentone
Yes. Mentone is in a Very High Fire Hazard Severity Zone, so any permit-triggered project must bring the entire structure into Chapter 7A compliance, including ember-resistant vents on the existing house. The county inspector will flag non-compliant attic and crawl-space vents at rough-in. That’s a whole-house vent replacement added to the scope, even though you only wanted a bedroom. Call (877) 610-1318 and we’ll tell you what your specific house will trigger before you commit.
A garage conversion ADU in Mentone runs $30,000 to $80,000. A new detached ADU runs $90,000 to $220,000. The conversion uses an existing footprint, so you avoid new foundation and site work. The detached ADU gives you a separate structure with its own setback and utility run, but the cost reflects deeper footings on expansive soils and full Chapter 7A construction from the ground up.
Because county inspectors in unincorporated Mentone require the entire structure to meet Chapter 7A ember-intrusion rules once any permit is pulled. On a 1950s or 1960s ranch with original unrated vents, that means swapping every attic and crawl-space vent to ember-resistant WUI models. It’s a real line item we catch early so it doesn’t become a change-order surprise at rough-in.
Usually not without an engineer’s evaluation and often some foundation upgrade. Mentone’s alluvial fan soils are expansive and poorly consolidated, and a 1950s ranch foundation was never designed for a second story’s dead and seismic loads. We order the soils report and a structural review before quoting so you know exactly what the existing slab and walls can carry. Call (877) 610-1318 for a free site walk.
Mentone is unincorporated San Bernardino County, which means county noise ordinances, not Redlands city codes. Standard allowed hours are 7:00 a.m. to 7:00 p.m. on weekdays, with Saturday hours typically allowed but more restricted, and Sundays generally quiet. The exact hours can shift based on county code and specific site conditions, so confirm before scheduling. We plan our Mentone work within county hours from day one, and we tell neighbors what’s coming before the compressor starts.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Mentone since 1998.