Fast, Reliable ADU Builders Across Highland
If you’re weighing a detached ADU or JADU on your Highland property, you’re probably discovering something quickly: this city plays by different rules than the rest of the Inland Empire. Half-acre lots, horse zoning, wells, septic systems, county permits. Most builders who work San Bernardino or Redlands don’t know what to do with a Greenspot Road property that still pulls water from a private well. We do. Sunstone ADU Builders works the full stretch of Highland, from the 1950s ranch tracts off Baseline to the newer subdivisions near Boulder Avenue, and we price every job against the lot’s actual conditions before we quote a structure. Call (855) 949-1913 and we’ll walk your property with you.
Why Sunstone ADU Builders Is Highland’s Preferred ADU Builders Company
Highland homeowners keep calling us for the same reason: we don’t treat an ADU like a generic backyard box. We treat it like a building that has to sit on your dirt, clear your septic, handle your wind, and match your property’s character. That means walking the leach field before we draw a single line. Checking whether your well pump has the capacity for a second dwelling. Grading a slope so runoff doesn’t pool against your foundation. Those are Highland problems, and they’re the ones that blow budgets when they’re missed.
Nate Holloway built Sunstone ADU Builders as an ADU-only shop. That matters here more than in most cities, because Highland permits often route through San Bernardino County rather than a city counter, and county reviewers ask different questions. Our team works that process weekly across Highland, so we know which septic setbacks trigger a survey and which grading plans get flagged. Homeowners in the east foothills and the older ranch neighborhoods tell us the same thing: quotes from out-of-town builders look lower until the well or septic upgrade shows up mid-permit. Our quotes include what the lot actually requires.
We’re an authorized builder for Abodu, Cover, and Dvele, and we also build traditional stick-frame units when the site calls for it. That matters on Highland acreage, where a prefab delivery sometimes can’t make the turn off a narrow dirt drive. We’ll tell you which method fits your lot, your budget, and your timeline, and we’ll finish the interior under the same contract. One contractor, start to finish. Call (855) 949-1913 for a free estimate.
Detached ADU in Highland
A detached ADU in Highland is the default choice for the half-acre and larger lots that run through the east side and up toward the foothills. These properties give you room to build 600 to 1,200 square feet of new structure while still keeping horse pens, RV parking, or a workshop, which is the whole reason many people bought in Highland in the first place. A detached ADU here typically runs $180,000 to $320,000 depending on size, finishes, and what the lot demands before we break ground.
What drives cost on a Highland detached ADU isn’t usually the framing. It’s the ground. Older foothill properties on wells and septic often trigger a mandatory water or sewer connection upgrade when you pull an ADU permit. That can add $15,000 to $40,000 before the first footing is poured. We scope those connections, the septic setbacks, and any required grading before we quote, so you’re not hit with a change order three months in.
Septic and well setbacks
Your leach field has a legal setback distance, and so does your well head. On a flat half-acre that’s usually manageable. On a sloping foothill lot off Greenspot Road, it can push your buildable area into a corner you didn’t expect. We walk the site, pull the records, and pin the pad location before plans are drawn.
Grading and equipment access
Highland lots slope toward the wash in plenty of places. That means a grading plan and a clear equipment path so a concrete truck doesn’t cross your leach field or tear up a graded pad. We handle both as part of the scoped quote.
JADU in Highland
A JADU in Highland works differently than a detached unit and often fits a different kind of property: the newer 1980s and 1990s subdivisions along the west side where yards are tighter and the house has an attached garage or a bonus room with its own access. A JADU converts existing space into a legal, separate dwelling, usually 400 to 500 square feet. In Highland, a JADU conversion typically runs $70,000 to $130,000, which makes it the lower-cost entry point for rental income or a family member who needs to be close.
What surprises Highland homeowners is that even a garage conversion can trip a service upgrade. If your panel is original to a 1960s ranch house, a second dwelling usually needs a 200-amp service and a separate meter. That’s routine here, but it’s a cost a general contractor down the hill won’t always flag. We scope it on the front end because we see it on nearly every older Highland property.
JADU permit path in Highland
The county requires owner-occupancy for JADUs in some zoning, so if you’re planning to rent both units out, we’ll walk you through what’s allowed before you spend money on drawings. Getting that wrong is the fastest way to stall a project at the counter.
Interior finishing under one roof
Because we finish kitchens and bathrooms in-house, a garage-to-JADU conversion doesn’t leave you hiring a second contractor to make it rental-ready. We build the walls, run the plumbing, tile the shower, and hang the cabinets under one contract.
Trusted Brands We Service in Highland
Highland’s lot variety means no single construction method wins. That’s why we’re authorized to build and install units from Abodu, Cover, and Dvele alongside traditional stick-built construction. If your site suits a prefab delivery, we’ll spec one of those brands and handle the installation, foundation, and finish work. If your drive or slope makes delivery impractical, we’ll frame it traditionally with James Hardie fiber cement siding so the exterior holds up to Highland’s heat and wind. We stock the trim, flashing, and fasteners those systems need locally, so we’re not waiting on a parts order to push a project forward in Highland.
Common ADU Builders Problems We See in Highland Homes
- Missed well and septic connections. The quote covers the ADU shell, then the county hits the permit with a mandatory water or sewer connection upgrade on an older foothill lot. The budget blows mid-permit because nobody looked at the lot records first.
- Wrong setbacks on acreage. A builder drops the ADU too close to a leach field or well head, and the plans get rejected or the pad has to move. On a sloped half-acre, that can eat the usable building area entirely.
- Under-built for heat and wind. Highland summers push past 100°F and Santa Ana winds hit hard at the base of the San Bernardino Mountains. Undersized insulation and missed wind-rated roof attachments leave the unit hot and the permit non-compliant.
- No grading or drainage plan. Open sloping lots shed water fast in winter. Without a grading plan, runoff pools against the new foundation or washes out the access path. We scope drainage before we pour.
Pricing for ADU Builders in Highland, CA
A JADU conversion in Highland runs $70,000 to $130,000. A detached ADU on a standard lot runs $180,000 to $320,000, and on a foothill acreage property with well, septic, and grading work, the full project can reach $350,000 to $450,000 once connections and site work are in. What moves the number in Highland more than finish level is what’s under the dirt: septic capacity, well service, slope, and access. We scope all of that before we write the quote, so the price you see is the price you’re building to. Call (855) 949-1913 and we’ll walk the lot and give you line-item numbers.
We Also Serve Cities Near Highland
Our ADU Builders team works Highland daily, and we also serve homeowners in San Bernardino, Muscoy, Redlands, and Loma Linda. If your property sits near the city line and you’re not sure which permitting path applies, call us and we’ll sort it out from the address.
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
Because so many Highland properties still run on private wells and septic systems, and an ADU permit frequently triggers a mandatory connection to municipal water or sewer, along with septic setback work. That’s a $15,000 to $40,000 line item that San Bernardino and Redlands parcels rarely carry. Call (855) 949-1913 and we’ll check your property’s records to see if it applies to you.
Usually yes, and that’s exactly the kind of site we work most in Highland. We pin the ADU pad clear of septic fields, well heads, and equestrian areas, then plan the equipment path so the concrete truck and material staging never cross your pens or your leach field.
It depends on your property’s zoning and whether it falls under San Bernardino County review or the city’s path. We determine that from your address before we draw plans, and we submit the right package to the right agency the first time.
We specify heavy attic insulation, shaded or low-E windows, and wind-rated roof attachments as standard on Highland builds, because the climate at the base of the mountains demands it. The exterior gets James Hardie fiber cement siding, which holds up to heat, wind, and fire exposure better than vinyl or wood.
Yes, and we scope the grading plan before we quote. We map the slope, set the pad elevation, and design drainage so water moves around the structure instead of against the foundation. On steeper foothill lots, we stage the material haul and equipment path to keep heavy trucks off unstable ground.
Call Sunstone ADU Builders in Highland
If you’re on a half-acre in Highland and tired of quotes that don’t include what the lot actually requires, call us. We’ll walk the property, check the well and septic records, flag any connection triggers, and give you a line-item estimate for a detached ADU or JADU that’s built for your site. Call (855) 949-1913 to schedule your free estimate.
Written by Nate Holloway, Owner at Sunstone ADU Builders, serving Highland, CA and the surrounding Inland Empire.