Fast, Reliable New Detached ADU Across Granada Hills
A new detached ADU in Granada Hills typically runs $285,000-$475,000 all-in for a custom build, or $195,000-$340,000 for a prefab or modular unit, with permit approval taking 4-7 months depending on whether your lot triggers City of LA or county jurisdiction. We’re Ellery ADU Studio, and our New Detached ADU team has designed, permitted, and built ADUs across Granada Hills since 2015 - from the ranch tracts near Granada Hills Charter High School to the foothill parcels off Balboa Boulevard. Dispatch and scheduling are coordinated from our Los Angeles office, and crews serve Granada Hills locally. Call (820) 444-6584 to schedule your free estimate.
Why Ellery ADU Studio Simi Valley Is Granada Hills’s Preferred New Detached ADU Company
We’ve completed over 900 ADUs across Southern California, and a significant share of those have been in the San Fernando Valley - including Granada Hills, Northridge, and Chatsworth. Our reputation here rests on two things: we quote a written price before any work starts, per Haven Standard Clause 1, and we deliver a documented photo record on every visit so you see what we found, not what we felt.
Granada Hills homeowners find us because they’ve already read the three-star reviews of contractors who went over budget or missed permit rejections. They want the permit set treated as the core product, not an afterthought. That’s what our design-build model delivers - drawings, permit set, and construction under one contract at one written price, eliminating the designer-versus-builder blame gap that derails most ADU projects.
Response time to Granada Hills is typically same-week for initial site visits. A live person answers calls 24/7 - no voicemail queue, no callback promise that doesn’t materialize.
Our local knowledge runs deep. We know the difference between a standard City of LA permit path and the county route that larger foothill parcels require. We’ve mapped post-1994 seismic retrofits that never made it into county records. And we’ve scoped equipment access for modular deliveries on narrow driveways off Chatsworth Street and Balboa Boulevard. This is the expertise that keeps Granada Hills projects on schedule.
Our New Detached ADU Services in Granada Hills
Custom Built ADU
Custom built ADUs are our most common request in Granada Hills, and for good reason. The neighborhood’s unusually large lots - many exceeding 10,000 sq ft - let us design units that don’t compromise on bedroom count, ceiling height, or outdoor space. A typical 1-bed custom detached ADU in Granada Hills runs $285,000-$365,000 all-in; a 2-bed unit runs $340,000-$475,000. These prices include the permit set, structural engineering, foundation, utility tie-ins, and final inspection.
Because Granada Hills sits almost on top of the 1994 Northridge epicenter, many homes here were structurally rebuilt or retrofitted mid-1990s - foundations, mudsills, and garage slabs were altered in ways that never made it into the original county records. A detached ADU here often starts with an engineer’s documentation of post-quake conditions rather than a clean-sheet design. This is compounded by the rarity of those 10,000+ sq ft lots, which make detached ADUs and even JADUs simultaneously feasible without lot-coverage waivers. We scope this seismic-history work upfront and build it into your written quote.
Prefab ADU Installation
Prefab ADU installation in Granada Hills typically runs $195,000-$290,000 for a studio or 1-bed unit, including foundation, utility connections, and permit compliance. We specify and coordinate systems from Cover, Dvele, and Mighty Buildings - brands whose panelized or volumetric units we can adapt to Granada Hills’s specific conditions.
The San Fernando Valley heat makes mechanical sizing critical. A prefab unit designed for coastal California will underperform here. We specify mini-split capacity, insulation R-values, and ventilation for 105-112°F summer days. Santa Ana wind events along the northern edge near the Santa Susana foothills also affect exterior material choices under LA’s Wildland-Urban Interface requirements. We handle this material specification in the same single contract.
Modular ADU
Modular ADUs - factory-built volumetric units delivered in sections - run $210,000-$340,000 in Granada Hills depending on bedroom count and finish level. The modular path works well here when equipment access is clear. But on deep lots with narrow side yards or soft, unimproved dirt driveways in the northern foothill edges, a standard concrete truck or modular delivery rig can get stranded. We scope this upfront. If needed, we line out crane rental or conveyor-pump costs in your written quote before you sign - no surprises mid-build, per Haven Standard Clause 5.
Studio ADU
Studio ADUs are the entry point for many Granada Hills homeowners testing the ADU market. A custom studio detached ADU typically runs $240,000-$310,000; a prefab studio runs $195,000-$250,000. On a 10,000+ sq ft lot, a studio ADU plus a JADU conversion of the existing garage is often feasible simultaneously - a combination that generates rental income while preserving the main house’s footprint. We verify lot coverage, setback, and utility capacity before quoting this path.
What happens when you call
- 1
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 Granada Hills
We specify and coordinate prefab and modular systems from Cover, Dvele, Mighty Buildings, Boxabl, Plant Prefab, Tuff Shed, and James Hardie - integrating whichever system fits your lot conditions and budget into the same single contract. For Granada Hills’s climate and seismic conditions, we often lean toward Cover’s panelized approach or Dvele’s steel-frame volumetric units, both of which handle the Valley’s heat expansion and our occasional seismic movement better than light-wood alternatives. We don’t push brands. We specify what the site demands, quote it in writing, and coordinate delivery and set ourselves.
Common New Detached ADU Problems We See in Granada Hills Homes
- Post-1994 slab and foundation unknowns. Many garage slabs and stem walls were rebuilt or releveled after the Northridge quake, sometimes unpermitted. The ADU footing design must document actual rebar and anchor-bolt conditions - not what the county’s older records show. We start with a test pit and structural engineer sign-off.
- Grading and drainage on open lots. Without a pre-construction topographic survey, a detached ADU pad can inadvertently dam seasonal sheet flow from the Santa Susana foothills, triggering county drainage corrections mid-build. We order the survey and design the pad grade before permit submission.
- Long material hauls and equipment access. Narrow side yards and soft, unimproved dirt driveways in the northern foothill edges can strand concrete trucks and modular delivery rigs. We walk the access route during scoping and line out crane or pump costs if needed.
- Heat and wildfire interface design. Granada Hills regularly hits 105-112°F in summer, and the northern edge sits under Wildland-Urban Interface requirements. Mini-split sizing, insulation, and exterior material choices aren’t afterthoughts here - they’re permit-critical design decisions.
Pricing for New Detached ADU in Granada Hills, CA
Here’s what a new detached ADU costs in Granada Hills, based on projects we’ve quoted and built in the 91344 ZIP and surrounding areas:
| ADU Type | Typical Range (All-In) |
|---|---|
| Studio ADU - Custom Build | $240,000 - $310,000 |
| Studio ADU - Prefab/Modular | $195,000 - $250,000 |
| 1-Bed ADU - Custom Build | $285,000 - $365,000 |
| 1-Bed ADU - Prefab/Modular | $210,000 - $290,000 |
| 2-Bed ADU - Custom Build | $340,000 - $475,000 |
| 2-Bed ADU - Modular | $260,000 - $340,000 |
These ranges include design, permit set, structural engineering, foundation, framing, MEP, finishes, utility tie-ins, and final inspection. What moves you within the range: site conditions (especially post-quake foundation documentation), finish level, and whether equipment access requires crane or pump rental. Under Haven Standard Clause 1, every project is quoted with a written price before any work begins - the words “call for a quote” do not appear on our site because the quote is the point. We also offer a Free Second Opinion on any written estimate already in hand. Call (820) 444-6584 for your written estimate.
We Also Serve Cities Near Granada Hills
Our crews work throughout the west San Fernando Valley. We also build New Detached ADU in Granada Hills for homeowners in Northridge, Chatsworth, Reseda, and Winnetka - each with its own permitting path and site conditions, each scoped with the same written-price guarantee.
Serving Granada Hills, CA - Our Local Coverage Area
We’re based in the Granada Hills 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 Granada Hills
Most Granada Hills parcels fall under City of Los Angeles jurisdiction, but larger foothill lots - particularly those north of Rinaldi Street or above 1,000 feet elevation near the Santa Susana foothills - can trigger Los Angeles County requirements instead. The county path adds roughly 3-5 weeks to plan check and requires a separate set of drainage and fire-access clearances. We determine your jurisdiction during the first site visit and build the correct permit timeline into your written quote. Call (820) 444-6584 to schedule that visit.
Yes, and it’s one of the most common issues we encounter here. On a half-acre parcel off Chatsworth Street in Granada Hills, we were scoping a 2-bed detached ADU when the owner mentioned the garage slab had been “re-poured after the quake” but had no paperwork. We dug a test pit and found a post-1994 stem wall with inconsistent rebar and no permit record, so before we could place the new unit we brought in a structural engineer to sign off on the existing slab and mapped the post-quake bolting and shear panels on the main house. The fix - a pin-and-epoxy retrofit of the old slab plus a new independent foundation for the ADU - added about three weeks of pre-construction scope, but it kept the county building department from rejecting the permit outright. We now budget for this possibility on every Granada Hills project. Call (820) 444-6584 and we’ll assess your slab conditions during the free estimate.
Yes, on most Granada Hills lots. The neighborhood’s large single-family lots - many exceeding 10,000 sq ft - mean most parcels can accommodate a detached ADU plus a JADU simultaneously without triggering lot-coverage or setback waivers. The JADU typically converts an existing attached garage or interior space, while the detached ADU occupies a rear or side yard. Combined rental income from both units often exceeds $4,000/month in the current Granada Hills market. We verify your specific lot coverage, setback, and utility capacity before quoting this dual-unit path. Call (820) 444-6584 to check your parcel.
We order a pre-construction topographic survey and design the ADU pad grade to maintain natural sheet flow. Without this step, a detached ADU pad can inadvertently dam seasonal runoff from the Santa Susana foothills, triggering county drainage corrections mid-build that add weeks and thousands to the project. Our written scope includes the survey, pad design, and any necessary French drain or daylight outlet work - priced before you sign, not discovered after. Call (820) 444-6584 for a written quote that includes drainage.
Mini-split sizing, insulation R-value, and exterior material selection are the three critical design decisions. A unit sized for coastal LA will fail in 105-112°F Valley heat. We specify 20+ SEER mini-splits with capacity for the load, R-19+ wall insulation, and reflective roofing. For parcels near the Santa Susana foothills, LA’s Wildland-Urban Interface requirements govern exterior material choices - non-combustible siding, ember-resistant vents, and defensible space planning. We handle all of this in the permit set, which is the core product of our design-build contract. Call (820) 444-6584 to review the specific requirements for your lot.
Ready to price a new detached ADU on your Granada Hills property? Call (820) 444-6584 to schedule your free estimate. You’ll receive a written, line-item quote before any work begins - per Haven Standard Clause 1 - and a 365-Day Done Right Promise backed in writing. We also offer a Free Second Opinion on any written estimate already in hand.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Granada Hills since 2015.