Fast, Reliable ADU Builders Across Highland
Adding an ADU in Highland means working with a builder who understands San Bernardino County’s hillside and fire-safety codes, not just someone who frames walls. We’re Camden ADU Builders, and we’ve spent enough time on Highland properties to know that the difference between a smooth build and a mess usually comes down to what happens before the foundation is poured. If you’re weighing a detached ADU or a JADU on your property in the 92346 ZIP, call (844) 747-5499 and we’ll walk you through what your specific lot actually allows, what it will cost, and which build path makes sense for your budget.
Why Camden ADU Builders Is Highland’s Preferred ADU Builders Company
Highland homeowners keep bringing us back for one reason: we don’t pretend every lot is flat and every house is ready for a second dwelling. The homes up near the base of the San Bernardino Mountains were built decades ago, and many of them need real electrical, drainage, and foundation work before an ADU can be permitted. We tell you that on the first visit, not after the drywall is open.
Noel Carrasco leads our builds, and his approach is exactly what Highland’s older housing stock demands: inspect first, write allowances into the contract, and get written approval before any change order touches the job. That’s not a sales pitch. It’s the only way to keep a hillside ADU project from running 30% over budget by month three.
Our familiarity with the neighborhoods along Baseline Street, Victoria Avenue, and the foothill communities east of the 210 means we already know what San Bernardino County will ask for on your specific parcel. That knowledge shortens plan check and keeps your project moving.
Detached ADU in Highland
A detached ADU in Highland is the most common route for homeowners with the lot space to support it, and in the foothill neighborhoods near the San Bernardino Mountains, that space often comes with a slope. On flat parcels near Victoria Avenue or along Baseline Street, a detached unit can sit on a standard slab foundation and move quickly. On hillside lots, expect stepped footings or a retaining wall, and plan for that cost from the start. A typical detached ADU in Highland runs $180,000 to $320,000, depending on slope, square footage, and finish level. The hillside sites add $15,000 to $40,000 for foundation work alone, and that’s before we talk about drainage correction or soil stabilization. We build detached ADUs as full-scope projects: foundation, framing, James Hardie fiber-cement exterior, electrical, plumbing, and interior finish, all handled by our crew rather than handed off to subcontractors who’ve never seen your street.
Foundation Work on Sloped Lots
Highland’s foothill parcels demand stepped foundations or retaining walls far more often than the flatland lots in San Bernardino or Muscoy. The county requires geotechnical review on many of these sites because drainage and soil stability directly affect foundation performance. We bring that requirement up before you sign anything, and we write the retaining wall or stepped footing allowance into your contract so it’s a known cost, not a surprise.
Hillside Drainage and Water Intrusion
Older Highland homes often have failing waterproofing, and when you add a second dwelling below grade on a slope, that problem doubles. We inspect the existing foundation’s drainage before design is finalized, and we correct it as part of the build. A drainage correction on a Highland hillside lot typically runs $4,000 to $11,000, and skipping it means water in your ADU within two winters.
JADU in Highland
A JADU in Highland is the lower-cost path to adding rentable or family space inside your existing home’s footprint, usually in a converted garage, basement, or attached bonus room. JADUs are capped at 500 square feet and must be within the existing structure, which makes them popular on older Highland properties where the house already has an underused attached garage. A typical JADU conversion in Highland runs $90,000 to $160,000, with costs rising when the existing structure needs electrical panel upgrades, new subfloor, or seismic reinforcement. On homes built in the 1960s and 1970s up near the foothills, the panel upgrade alone is often $3,500 to $7,000, because the original 100-amp service can’t legally carry a second dwelling.
Code Upgrades You’ll Actually Trigger
Opening walls in a 1960s or 1970s Highland home turns into a code review, and that review turns into required upgrades. The big ones we see every week are electrical panels, smoke and carbon monoxide detector hardwiring, and water heater strapping. We include these as allowances in the contract, and we price each one before we start, so the JADU budget doesn’t climb while you’re watching.
Attached Garage Conversions
The attached garage is the natural JADU site on most Highland lots, but those garages were never insulated, often share a wall with the main panel, and sometimes have slab cracks from decades of Santa Ana-season ground movement. We insulate to current Title 24 energy standards, correct the slab where needed, and finish the interior with the same kitchen and bath crew that builds our detached units.
Trusted Brands We Service in Highland
Because we work across manufacturers rather than for one, we can tell you honestly when a Cover unit’s precision engineering fits your site better than a Dvele premium modular build, or when a Mighty Buildings panelized shell keeps a budget-accessible project on schedule. For Highland homeowners who want a smaller footprint at a lower price point, we also run Tuff Shed conversions through the same full-scope process. Our ADU Builders team stocks the common connection hardware and finishing materials for these brands, which keeps change-order delays short on Highland sites. The recommendation you get is driven by your lot, your budget, and your timeline, not by a dealer margin.
Common ADU Builders Problems We See in Highland Homes
- Hillside drainage failures. Highland’s foothill lots concentrate runoff toward the foundation, and older homes often lack proper waterproofing or drainage correction. We fix this before framing starts, not after the first rain season soaks the new unit.
- Electrical panels at capacity. Homes built between the 1950s and 1980s in the 92346 ZIP frequently carry 100-amp panels that can’t support a second dwelling. We price the panel upgrade as a line item, and we pull the permit for it as part of the build.
- Sloped foundations drawn flat. Builders who treat Highland like flatland get foundation cracks and permit rejections. San Bernardino County’s hillside review requires stepped footings or retaining walls on many sites, and we design for that from the first site visit.
- Fire-safety requirements underestimated. Highland’s proximity to wildland areas means stricter setbacks, defensible space clearance, and sometimes ignition-resistant materials. We know what the county will demand on your parcel and we build it into the design, not after plan check kicks it back.
Pricing for ADU Builders in Highland, CA
Here are the numbers we give Highland homeowners, in writing, before any contract is signed. A JADU conversion runs $90,000 to $160,000. A detached ADU on a flat parcel runs $180,000 to $260,000. A detached ADU on a sloped foothill parcel runs $220,000 to $320,000, because foundations, drainage, and retaining walls add $15,000 to $40,000 before framing begins. The older the home, the more you should budget for electrical, waterproofing, and code-triggered upgrades: $8,000 to $25,000 depending on what the inspection turns up. We do not bid low and change-order you later. We write the allowances into the contract, and every change is priced and approved in writing before we touch it. Call (844) 747-5499 for a free estimate on your exact property.
We Also Serve Cities Near Highland
While this page is for Highland, our crews work the surrounding area daily. We serve Highland alongside San Bernardino, Muscoy, Redlands, and Loma Linda. That matters if your property sits near a city boundary or your project needs county-level approvals that a neighboring city contractor would rarely touch.
Serving Highland, CA — Our Local Coverage Area
We’re based in the Highland 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 ADU Builders in Highland
You should expect the county to require electrical panel upgrades, hardwired smoke and carbon monoxide detectors, and often new subfloor or wall reinforcement once framing is exposed. On Highland homes from that era, we typically find undersized wiring and original waterproofing that has failed. We write these items into the contract as allowances before we open any wall, and we price each one for your written approval before work proceeds.
Highland’s foothill parcels trigger geotechnical review, which usually means stepped foundations or retaining walls rather than a standard slab. The county also enforces fire-safety setbacks and sometimes ignition-resistant exterior materials up near the wildland interface. Plan for these requirements from day one, because treating the site as flat adds weeks to plan check and thousands to the foundation budget. Call (844) 747-5499 and we’ll tell you which requirements apply to your parcel.
Rarely. Most Highland homes built before 1990 run 100-amp panels, and a JADU with a kitchenette, lighting, and HVAC draws more than the remaining capacity allows. A panel upgrade usually costs $3,500 to $7,000, and it’s often the first item on the permit. We inspect your panel before quoting so you know whether the upgrade is required or optional for your JADU.
Sloping terrain, expansive soil, and concentrated drainage are the three big ones. We regularly see retaining walls that were never engineered, slab cracks from seasonal soil movement, and waterproofing that failed decades ago. On sloped Highland lots, we recommend a geotechnical review and a stepped foundation or retaining wall designed for the specific soil, not a stock detail from a flatland builder.
We inspect the site before the contract is signed, and we write allowances into the contract for the known unknowns: electrical, drainage, seismic strapping, and rot. If something new shows up, we stop work, price it in writing, and get your signed approval before we continue. You never pay for a change you didn’t approve. For a quote on your Highland property, call (844) 747-5499.
Ready to Plan Your ADU in Highland?
Whether you’re looking at a detached unit on a foothill slope or a JADU in a 1960s attached garage, we’ll give you honest numbers and a build path that makes sense for your lot. Call (844) 747-5499 to schedule your free estimate. Noel Carrasco and our crew serve Highland and the surrounding cities, and we’re ready to walk your property, review the county requirements, and put a written scope together.
Written by Noel Carrasco, Owner at Camden ADU Builders, serving Highland, CA.