Fast, Reliable Garage Conversion ADU Across Morgan Hill
Garage conversion ADUs in Morgan Hill typically run $180,000-$260,000 all-in, drawings through final inspection, with septic-related site work adding $15,000-$45,000 on foothill-edge properties that are not connected to city sewer. Ellery ADU Studio coordinates the entire conversion under one contract, including Santa Clara County Environmental Health percolation testing when your parcel requires it. We are a design-build studio, not a contractor who subs out the drawings to someone you’ll never meet. Call (971) 497-2402 and we’ll walk you through what applies to your specific Morgan Hill parcel.
Why Ellery ADU Studio Is Morgan Hill’s Preferred Garage Conversion ADU Company
Since 2015, Ellery ADU Studio has designed, permitted, and built more than 900 ADUs across the Bay Area, with a substantial share on Morgan Hill acreage and large-lot parcels. Our clients in Morgan Hill tend to be homeowners who bought between 2015 and 2025 and are now weighing an ADU as a long-term asset. They research before they call. They want a written price, not a phone call that ends in “we’ll send someone out.” That is exactly how we operate.
Nadia Ellery founded the studio with a specific conviction: the permit set is the product. Not an afterthought, not a line item. When you work with us on a Garage Conversion ADU in Morgan Hill, you receive drawings stamped for Santa Clara County review, a written scope that locks under Haven Standard Clause 1, and a documented photo record of every site visit. You will not chase a designer for revisions while a builder waits across town. One contract. One written price. That’s the model.
We’ve navigated enough Morgan Hill projects to know what most general contractors miss: a percolation test that fails six weeks into design, a leach field that is already at capacity, a grading plan that triggers county drainage review. We scope those before quoting, not after. For Morgan Hill homeowners, that early due diligence is often the difference between a project that starts on schedule and one that stalls for a season.
Our Garage Conversion ADU Services in Morgan Hill
Most Morgan Hill garage conversions fall into one of four categories. Here is how each applies to the homes we see along East Dunne, Uvas Road, and the wider foothill-edge corridor.
Attached Garage Conversion
For the 1970s-1990s ranch-style homes that dominate Morgan Hill subdivisions, an attached garage conversion is often the most economical path to a one-bedroom ADU. The existing roof, foundation, and one shared wall reduce framing and site work. On parcels connected to city sewer, we typically see attached conversions run $160,000-$210,000 in Morgan Hill. On septic systems, budget for the county percolation test and possible leach field review before we lock the written price.
Detached Garage Conversion
Morgan Hill’s older subdivisions and rural-residential parcels frequently retain detached garages and equipment sheds that make strong conversion candidates. Provided the slab is within thickness range and the framing is sound, a detached garage conversion in Morgan Hill runs $200,000-$260,000, with utility trenching and any grading correction accounted for. If the slab is under-specified for habitable space, we rebuild it with deeper footings, which we scope and price before any work starts.
Carport Conversion
Carport conversions make sense on Morgan Hill lots where the carport was built as a flat-roof addition, common on 1980s and 1990s homes in the central neighborhoods. We frame in the walls, upgrade the roof assembly, and bring the envelope to Title 24 standards. Because Morgan Hill sees summer highs in the mid-90s to low 100s°F, we right-size the mini-split heat pump rather than treating cooling as a line-item afterthought. A carport conversion in Morgan Hill typically falls between $140,000 and $185,000.
Garage Partition & Bathroom Add
When a Morgan Hill homeowner wants to keep part of the garage for storage or workshop space, we partition the structure and add a full bath for a Junior ADU. This is common on half-acre parcels where the detached garage is oversized. The work requires a separate entrance, a wet wall, and an electrical subpanel, plus the same septic leach field capacity review that applies to any dwelling unit in the county. Budget $90,000-$140,000 depending on how much of the original garage remains unconditioned.
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 Morgan Hill
We specify and coordinate prefab and modular systems from Cover, Dvele, and Mighty Buildings within the same single contract when a Morgan Hill project calls for a factory-built panel or module. That means we handle the foundation, site work, utility connections, and final inspection while the manufacturer builds the shell. For Morgan Hill clients, this reduces on-site framing time by weeks and keeps the project moving during the dry summer months when local crews are stretched across the county. You are not left to coordinate between a modular company and a general contractor. It is all under our contract, at our written price.
Common Garage Conversion ADU Problems We See in Morgan Hill Homes
- Failed percolation tests on East Dunne and Uvas Road parcels. The existing leach field may be sized for the original house only. A garage conversion ADU adds a second dwelling unit, which triggers a county capacity review. If the field fails, you are financing an expansion before we can pull the ADU permit.
- Under-specced cooling in converted detached garages. Morgan Hill regularly hits 100°F in summer, and an original detached garage has minimal insulation. Without a properly sized mini-split and a real thermal envelope, the ADU is unusable July through September.
- Winter drainage on low-lying lots near Llagas Creek and Coyote Creek. Foothill runoff and seasonal flooding affect foundation design and ADU siting. We flag this during the initial site walk, not after the county comments on the permit set.
- Slab thickness below habitable standard. Many Morgan Hill detached garages built in the 1970s and 80s sit on 3- to 4-inch slabs. If yours is under range, we price a slab replacement with deeper footings at the quote stage so there is no change order later.
Pricing for Garage Conversion ADU in Morgan Hill, CA
Here is what we tell Morgan Hill homeowners, in writing, before any work begins:
- Attached garage conversion, standard scope: $160,000-$210,000
- Detached garage conversion, on-grade slab: $200,000-$260,000
- Garage partition with JADU and full bath: $90,000-$140,000
- Septic percolation test and leach field capacity review: $3,000-$8,000
- Leach field expansion (if required): $25,000-$45,000
- Grading and drainage correction on sloped lots: $10,000-$35,000
Every dollar figure above is written into the contract before the first day of work. That is Haven Standard Clause 1, and we have never quoted a Morgan Hill project without it. You will not get a price range from us and then a change order two weeks in. We walk your parcel, we review county record, and we present the number. Call (971) 497-2402 to start that process. Estimates are free, and if you already have a written estimate from another firm, we will review it for free too.
We Also Serve Cities Near Morgan Hill
Our crews serve Morgan Hill, Gilroy, Watsonville, Los Gatos, and Campbell, with dispatch coordinated from our San Francisco Bay Area office. If you are in one of the surrounding cities and comparing garage conversion approaches, you can see how we work with the same single-contract model across the broader region on our Garage Conversion ADU in Morgan Hill page.
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 - Garage Conversion ADU in Morgan Hill
Most likely yes. Uvas Road and the surrounding foothill-edge parcels sit on private septic systems, and Santa Clara County Environmental Health requires a percolation test and leach field capacity review before any ADU permit can advance. We order that test during the design phase, not after the permit set is drawn. Call (971) 497-2402 and we will explain what applies to your parcel.
A failing leach field can push your groundbreaking back by a full construction season. We scoped a detached garage conversion off Uvas Road where the existing leach field failed a percolation test. We paused the garage work, coordinated a county-approved leach field expansion, and then rebuilt the slab with deeper footings. That project finished eight months later than a sewer-connected San Jose conversion would have. If your Morgan Hill parcel might have a marginal leach field, we test early. It is cheaper to know in month one than month six.
Sloped lots in the Gavilan foothills move water downhill, and a converted garage ADU changes where that water goes. If the existing slab drains toward the foundation, or if winter runoff from the hillside collects against the new wall, the county will not sign off, and the foundation will fail early. We scope grading and drainage at the initial site walk and include it in the written price. For Morgan Hill projects on sloped parcels, this line item typically runs $10,000-$35,000.
Yes, provided the leach field has capacity for the additional dwelling unit. The county reviews both the percolation rate and the existing field size before permitting a JADU on septic. We have converted attached garages into JADUs on Morgan Hill acreage parcels where the field passed the capacity review with room to spare. If it fails, we can scope a leach field expansion as part of the same contract. Call (971) 497-2402 for a written assessment of your specific parcel.
Expect to pay $15,000-$45,000 more in Morgan Hill on a septic-connected acreage parcel than on a sewer-connected San Jose lot of similar size. The difference comes from percolation testing, possible leach field expansion, utility trenching across a larger lot, and grading or drainage work on sloped terrain. We show you those line items in writing before you commit, so you know exactly what the Morgan Hill site conditions add. Call (971) 497-2402 to schedule a free estimate.
If you are ready to talk numbers, call (971) 497-2402. We’ll walk your Morgan Hill parcel, check the county record, and put a written price in front of you. No phone-tree runaround. A live person answers.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Morgan Hill and the surrounding Bay Area since 2015.