Fast, Reliable New Detached ADU Across Morgan Hill
A new detached ADU in Morgan Hill typically runs $275,000 to $420,000 all-in, drawings through final inspection, depending on whether your lot is on city sewer or a private septic system. We’re Ellery ADU Studio, a design-build practice that has designed, permitted, and built 900+ ADUs since 2015 under a single contract at a single written price. If you’re on a foothill-edge or East Dunne Avenue parcel, call us at (971) 497-2402 before you spend a dollar on plans: the septic situation on your lot will drive your timeline more than any other single factor, and we scope it on day one.
Why Ellery ADU Studio Is Morgan Hill’s Preferred New Detached ADU Company
Morgan Hill homeowners research before they call. They’ve read the three-star reviews on other ADU firms, they know the horror stories about designer-versus-builder finger-pointing, and they want the price on the page. That’s exactly how we work. Every New Detached ADU we build in Morgan Hill starts with a written price before any work begins, per Haven Standard Clause 1. No “call for a quote,” no vague estimates. You get a written scope and a written price, and the drawings, the permit set, and the construction are one contract. If the designer and the builder are the same studio, there’s nobody to blame but us, and that’s the point.
Our crews serve Morgan Hill directly from our Bay Area dispatch office, and we know the terrain: the sloped lots off East Dunne, the half-acre parcels along Uvas Road, the older ranch subdivisions near Llagas Creek. We’ve pulled permits through Santa Clara County for detached ADUs on septic, on sewer, on hillsides, and on flat lots. A live person answers our phones 24/7. You won’t get a voicemail queue.
Our New Detached ADU Services in Morgan Hill
Custom Built ADU
A custom built ADU in Morgan Hill runs $300,000 to $420,000 for a 1-bed or 2-bed unit, depending on site conditions and septic scope. This is the right path when your lot has the space and you want a unit sized to the parcel, not to a modular factory spec. On foothill-edge lots near Uvas Road, we frame with hot-dip galvanized post bases and stainless-steel roof fasteners from the start, because the salt air that drifts up from Monterey Bay through the Gavilan foothills chews through zinc-plated hardware within five years.
Prefab ADU Installation
Prefab ADU installation in Morgan Hill runs $250,000 to $360,000, including site prep, foundation, utility connections, and the prefab unit itself. We specify and coordinate systems from Abodu, Cover, Dvele, and Mighty Buildings within our single contract. Prefab works well on flat, sewer-connected lots in the older subdivisions west of downtown Morgan Hill. On hillside parcels with grading and utility extensions, the savings can evaporate, which is why we run the site analysis before recommending the system.
Modular ADU
Modular ADU construction in Morgan Hill runs $260,000 to $380,000, with the same single-contract structure. The advantage on a lot with good access is a shorter on-site build window, but Morgan Hill’s sloped terrain and septic requirements can add crane costs, grading, and leach field work that a flat San Jose lot would never see. We don’t sell you a modular unit until we’ve walked the site and confirmed the access path, the crane pad, and the septic capacity.
Studio ADU
A studio ADU in Morgan Hill runs $225,000 to $300,000 for a roughly 400 to 600 sq ft unit. This is the workhorse for homeowners who want rental income or a quiet home office without the footprint of a 2-bed. On the 1970s ranch lots that dominate Morgan Hill’s housing stock, a detached studio tucks neatly into the side yard where an old equipment shed used to sit. We handle the demolition, the new foundation, and the utility extension as part of the written scope.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Morgan Hill
We specify and install prefab and modular systems from Abodu, Cover, Dvele, and Mighty Buildings for Morgan Hill homeowners, and we handle the site prep, foundation, and utility work those systems require. When a manufacturer’s spec doesn’t match Morgan Hill’s conditions, we say so in the written scope and adjust the materials accordingly. That means marine-grade window flashing on south-facing elevations, stainless-steel fasteners on roof panels, and sealed paver joints on paths where Llagas Creek floodwater is a winter reality. We keep the documentation on every system we install, so you know exactly what’s on your ADU and what’s covered.
Common New Detached ADU Problems We See in Morgan Hill Homes
- Corroded roofing fasteners on east-facing slopes near Uvas Road. The salt air that drifts inland from Monterey Bay through the Gavilan foothills attacks zinc-plated hardware fast. We see loose roof panels and rusted fastener heads within five years. We spec stainless-steel fasteners on every detached ADU we frame in Morgan Hill, on every slope, by default.
- Failed leach fields on East Dunne and foothill-edge parcels. A private septic system that passed inspection in 1985 may not handle the added load of a new ADU. Santa Clara County Environmental Health requires percolation tests and capacity studies before a permit advances. We coordinate that early so you don’t lose a season.
- Warped vinyl window frames on south-facing detached ADUs. Morgan Hill’s summer highs in the mid-90s to low 100s bake standard vinyl sashes. Seals fail, frames warp, and by year three the windows don’t close square. We spec aluminum-clad wood or marine-grade composite frames on south-facing elevations, and we size the mini-split system for the thermal load, not the square footage formula.
- Heaved paver paths in low-lying areas near Coyote and Llagas creeks. Unsealed paver joints let winter floodwater undermine the base. Within two rainy seasons the path heaves and the concrete cracks. We seal the joints and grade the base so water moves away from the ADU, not under it.
Pricing for New Detached ADU in Morgan Hill, CA
Here are the ranges we quote in Morgan Hill today, written price, no surprises:
- Studio ADU (400-600 sq ft): $225,000-$300,000
- Prefab ADU (Abodu, Cover, Dvele, Mighty Buildings): $250,000-$360,000
- Modular ADU (1-bed or 2-bed): $260,000-$380,000
- Custom Built ADU (1-bed or 2-bed): $300,000-$420,000
The biggest swing factor in Morgan Hill is the septic situation. If your lot is on city sewer, the range sits at the lower end. If you’re on a private leach field off East Dunne, Uvas Road, or a foothill-edge parcel, add $15,000 to $40,000 for the percolation test, the capacity study, and any leach field expansion the county requires. We put that scope in writing before we start, per Haven Standard Clause 1. Call (971) 497-2402 for a written estimate. If you already have a written estimate from another firm, bring it in for a Free Second Opinion.
We Also Serve Cities Near Morgan Hill
Our Morgan Hill crews also cover Gilroy, Watsonville, Los Gatos, and Campbell for new detached ADU work. Each city has its own permit path and site conditions, and we’ve pulled permits in all of them. The septic requirement that dominates East Dunne and Uvas Road work in Morgan Hill doesn’t apply the same way in sewer-connected Los Gatos or Campbell, and that changes the timeline and the price.
Serving Morgan Hill, CA - Our Local Coverage Area
We’re based in the Morgan Hill 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 - New Detached ADU in Morgan Hill
On an East Dunne Avenue lot with a private septic system, the Santa Clara County Environmental Health percolation test and capacity study add 6 to 14 weeks to the pre-permit phase, and if the leach field is undersized, the expansion adds 3 to 6 months and $20,000 to $40,000 before groundbreaking. We scope the septic requirement on day one, not after the drawings are done, so the schedule we give you is the schedule that holds. Call (971) 497-2402 and we’ll walk your lot before you spend on plans.
We spec stainless-steel roofing fasteners and hot-dip galvanized post bases on every detached ADU near Uvas Road, on every slope. The salt air that drifts up from Monterey Bay through the Gavilan foothills corrodes zinc-plated hardware within five years, causing loose roof panels and rusted fastener heads. The coastal-spec fastener package adds $800 to $1,500 to the build, and it’s written into the scope from the start, not added as a change order later.
On a sloped Morgan Hill hillside lot, a modular ADU often costs the same as or more than site-built, because the grading, crane pad, and foundation work eat the factory savings. We run the site analysis before recommending the system, and the written price reflects the real site, not a manufacturer’s flat-lot brochure. If the numbers say site-built, we tell you that in writing. Call (971) 497-2402 for a written estimate on your specific lot.
We spec aluminum-clad wood or marine-grade composite window frames on south-facing elevations near Coyote Creek, not standard vinyl. Morgan Hill’s summer highs in the mid-90s to low 100s warp vinyl sashes within three years, and winter storms push water through failed seals. The upgraded frames add $400 to $900 per opening, and they’re part of the written scope from the start.
On a 1970s ranch lot in Morgan Hill, a detached garage conversion is often the right move if the slab is sound and the structure is square, and it runs $180,000 to $280,000, less than new construction. Our crews check the slab thickness, the existing electrical service, and the septic or sewer connection before we recommend conversion versus new build. If the slab is shot or the utility run is prohibitive, we tell you in writing. Call (971) 497-2402 and we’ll inspect the garage before you commit.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Morgan Hill since 2015.