Fast, Reliable ADU Builders Across Highland
Adding an ADU in Highland, CA starts with a question most homeowners haven’t considered: can your 1960s-era electrical panel and sewer line actually support a second dwelling? That’s where we come in. Buena Park ADU Builders works across eight ADU brands, from Tuff Shed to Boxabl, and we’ve built enough units in Highland to know that the lot, the trees, and the age of the main house shape the project more than any catalog photo ever will. Call (877) 265-7231 and we’ll walk your property first, not after you’ve signed.
Why Buena Park ADU Builders Is Highland’s Preferred ADU Builders Company
Highland homeowners call us because we don’t start with a brochure. We start with an inspection of what’s already underground and behind the walls. The 92346 zip code is full of 1950s and 1960s ranches that were framed and wired for a single household, and a detached ADU changes that math fast. Noel Carrasco, our owner, has walked enough Highland lots to know which panels will pass a second-meter inspection and which ones won’t. That’s the difference between a quote that holds and one that doubles mid-build.
We’re not a general remodeling outfit that added ADUs as a side service. ADU construction and the kitchen and bath remodeling that often accompanies it are what we do. When a Highland homeowner asks us to quote a JADU or a detached studio, we’re looking at it through the lens of someone who has built with Mighty Buildings, Plant Prefab, and Boxabl on lots exactly like theirs. That brand-agnostic experience means the recommendation fits the property, not our inventory.
Response time to Highland from our Buena Park base is straightforward: we schedule inspections within days of a call, and we show up when we say we will. Our customers in Highland keep calling back because we document what we find, write allowances into the contract for the unknowns, and price changes in writing before any work moves forward.
JADU in Highland
A JADU in Highland is the fastest path to a legal second unit when the main house has an existing bedroom, garage, or bonus room that can be converted within the footprint. On most mid-century Highland properties, that’s a garage conversion or a bedroom split that dedicates a kitchenette and separate entrance. The unit stays attached, which changes the utility conversation entirely.
Costs for a JADU in Highland typically run $80,000 to $140,000 depending on whether the space needs a new subpanel, independent heating and cooling, or a kitchenette that meets current code. That range assumes we’re not opening walls to replace cloth-insulated wiring. When we do find it, the scope adjusts, but it adjusts in writing before any demo starts.
What a JADU inspection actually covers
We open access panels, check the panel schedule, and trace the sewer path before we commit to a number. On older Highland homes, the kitchenette often shares a wall with the original bathroom plumbing, which can save real money. Other times it shares a wall with asbestos-era drywall, and we price remediation explicitly.
When a JADU makes more sense than a detached unit
Small lot? Preserve the backyard? Need a unit a parent or adult child can use without a separate meter? A JADU avoids the full utility upgrade a detached ADU often triggers in Highland, because it can be served as a sub-metered or shared-service unit under specific conditions. We’ll walk through that with you, not around it.
ADU Plans in Highland
ADU Plans in Highland are not a formality; they’re the document that determines whether your project clears the city’s planning and building review without a second or third resubmission. Highland’s older lots, mature tree placements, and setback patterns mean a plan drawn for a generic Southern California lot won’t pass here.
We produce or coordinate ADU plans that account for the actual sewer lateral location, the drip line of existing citrus trees, and the existing panel’s capacity in 92346. Plan costs in Highland typically run $6,000 to $15,000 for a detached unit depending on whether structural engineering, Title 24 energy calculations, and utility upgrade drawings are required.
Why the site plan drives everything in Highland
On a mid-century Highland lot, the ADU pad’s placement is often decided by what’s already in the ground: an old clay sewer line, a root system from a 50-year-old orange tree, a drainage swale that carries winter runoff toward the back fence. The site plan reflects those realities. We flag them before the plan set is submitted, not after the city kicks it back.
Plan sets that include the upgrades, not just the box
A Highland ADU plan set we’re comfortable submitting includes panel upgrade drawings when the main service is 100 amps, sewer reroute details when roots or grade changes require it, and drainage details that account for clay soil. That’s the difference between a plan that passes and a plan that’s just a pretty floor layout.
Trusted Brands We Service in Highland
We install and finish units from brands Highland homeowners are already researching: Mighty Buildings for panelized, high-performance envelopes; Boxabl for compact, factory-finished units; Plant Prefab for architect-driven designs. Because we work across these systems rather than repping one, we’ll tell you honestly when a Tuff Shed Studio is the right budget move and when a premium prefab shell is worth the added cost. We also stock common installation hardware and replacement parts for these systems locally, so a warranty follow-up or field adjustment in Highland doesn’t mean waiting on a freight shipment from out of state.
Common ADU Builders Problems We See in Highland Homes
- Electrical panels that can’t feed a second meter. Highland’s 1950s and 1960s stock commonly carries 100-amp panels. A detached ADU with its own meter almost always pushes you to a 200-amp main service, and that’s an upgrade you want priced on day one, not discovered after trenching starts.
- Sewer laterals threaded through mature citrus root zones. Legacy orange and grapefruit trees across Highland’s residential lots send roots into old clay and cast-iron lines. A pre-pour camera inspection catches this before the foundation is in, and rerouting outside the root zone keeps the trees alive and the inspection clean.
- Winter drainage failures on clay-heavy soil. Highland’s clay soil holds water through the winter rains. Cutting an ADU pad changes the grade, and if the drainage plan wasn’t designed for that soil type, you’ll find water against the foundation wall in February. We specify drainage at plan stage, not as a field fix.
- Framing and waterproofing that looks fine but isn’t. When an attached JADU ties into an existing wall, we open the exterior cladding and find failed flashing, dry rot, or missing moisture barriers more often than not. Pricing that repair before demo matters. So does not pretending it won’t be there.
Pricing for ADU Builders in Highland, CA
Let’s be direct about what ADUs cost in Highland. A detached studio ADU typically runs $180,000 to $260,000. A one-bedroom detached unit runs $220,000 to $320,000. A JADU conversion inside the existing home footprint runs $80,000 to $140,000. Those numbers assume a full utility upgrade where required, which on most mid-century Highland lots means a panel swap and often a sewer line update.
What moves the number? The panel’s current capacity, the sewer lateral’s condition, the distance from the ADU pad to the main service, and whether the lot’s trees force a longer or deeper trench. We write allowances for each of those into the contract so the quote doesn’t surprise you. Call (877) 265-7231 for a free estimate, and we’ll walk your specific lot and give you numbers that hold.
We Also Serve Cities Near Highland
Our ADU work takes us across the Inland Empire. We serve ADU Builders projects in San Bernardino, Muscoy, Redlands, and Loma Linda, bringing the same inspection-first process to older housing stock throughout the region. If you’re in Highland or any neighboring city, the conversation starts the same way: with a look at what’s already on the property. Reach us at (877) 265-7231.
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
A Highland ADU often costs more than the initial quote because the quote wasn’t based on an inspection of the original electrical panel, sewer lateral, and drainage conditions. Mid-century Highland homes frequently need a 200-amp panel upgrade, a sewer reroute around mature tree roots, and grading corrections for clay soil. Our process prices these as written allowances in the contract before work begins, so the final number reflects the real scope, not an optimistic guess. Call (877) 265-7231 for a quote grounded in what’s actually on your lot.
Yes, we can build a detached ADU around mature citrus trees in most cases. On a 1960s ranch near the Baseline corridor, our crew found the sewer line threaded between two mature trees, so we priced the reroute before demolition and ran the new line outside the root zone. The trees stayed, and the inspection passed. Foundation placement and sewer routing adjust around the trees, not through them. Call (877) 265-7231 and we’ll walk the lot with you to see what’s feasible.
A Highland ADU permit triggers smoke and carbon monoxide upgrades in the main house, tempered glass where required, and often a panel upgrade if the main service can’t support a second dwelling. If the tie-in wall reveals cloth-insulated wiring or failed waterproofing, those get repaired to current code while the wall is open. We price these as allowances so they don’t arrive as surprises. Call (877) 265-7231 to review what your specific home will need.
Not always. A JADU inside the existing home footprint can often share the main panel and water service under California code, which means the full panel-and-meter upgrade a detached unit requires may not be necessary. That said, if your Highland home still has a 60-amp or 100-amp panel feeding the original single household, even a JADU kitchenette can push the load calculation over. We’ll check the panel and load before we promise anything. Call (877) 265-7231 for an honest read on your specific setup.
We design drainage at plan stage, not after the pad is cut. Highland’s clay soil holds water, and winter rains expose any grading mistake quickly. On older properties, we specify swales, perimeter drains, and sometimes a dry well sized for the soil’s actual infiltration rate. The drainage plan is part of the submitted plan set, so the city reviews it too. Call (877) 265-7231 to talk about what your lot’s drainage will need.
Written by Noel Carrasco, Owner at Buena Park ADU Builders, serving Highland since the company’s founding.