ADU in Agoura Hills, CA
A Junior ADU & Interior Conversion in Agoura Hills typically runs $85,000-$165,000 all-in, drawings through final inspection, while ADU Site Prep & Utilities usually adds $25,000-$75,000 depending on fire-hardening requirements and utility distances. Virtually all of Agoura Hills sits in a High or Very High Fire Hazard Severity Zone, so every ADU must meet Chapter 7A ignition-resistant standards that flatland neighbors simply don’t face. We’re Ellery ADU Studio, and we route permit applications through LA County’s Calabasas district office daily. Call (805) 301-9518 for your written estimate.
Why Agoura Hills Homes Are Different
Agoura Hills was built out largely between the mid-1970s and mid-1990s as tract suburban development, ranch-style and California contemporary homes on lots of 7,000 to 15,000+ square feet. That generous lot size tempts homeowners toward detached ADUs, but the attached two-car garages common to these tracts are more often the practical conversion target.
The city contracts with LA County Department of Public Works - Building and Safety rather than running its own department. Plan checkers at the Calabasas district office apply LA County’s WUI overlay on top of state ADU law. Projects that would clear quickly in city-run jurisdictions often need a fire-resistive construction compliance report before county staff accepts the application as complete.
Summer temperatures in these canyon-framed valleys regularly exceed 95°F, and the 2018 Woolsey Fire left homeowners acutely aware of defensible space rules. The 100-foot clearance zones constrain where detached ADUs can sit, while Santa Ana wind exposure pushes mechanical designs toward robust HVAC and attic ventilation for south- and west-facing hillside lots.
Our Main Agoura Hills Services
Agoura Hills homeowners call us most often for these three services, each with its own dedicated page and pricing.
ADU Design & Permitting in Agoura Hills
Our permit set is the core product, not an afterthought. For Agoura Hills, we prepare fire-resistive construction compliance reports alongside standard Title 24 energy calculations, because LA County’s WUI overlay adds a layer most city-run departments skip. Every set is submitted through the Calabasas district office with a written price locked before any work begins. ADU Design & Permitting in Agoura Hills.
Garage Conversion ADU in Agoura Hills
The attached two-car garages built into Agoura Hills tracts from the 1970s through 1990s are prime conversion candidates, but original slab-on-grade foundations and electrical panels sized for single-family use often need upgrading first. We assess existing conditions during our first site visit and document what we find with photos you receive. Garage Conversion ADU in Agoura Hills.
New Detached ADU in Agoura Hills
Generous lot sizes accommodate detached units, but fire-hardening under Chapter 7A adds cost and design constraints absent in flatland cities. Ember-resistant vents, Class A roofing assemblies, and one-hour exterior wall ratings are non-negotiable here. We coordinate these requirements into a single contract with one written price. New Detached ADU in Agoura Hills.
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.
Junior ADU & Interior Conversion in Agoura Hills
Junior ADU & Interior Conversion in Agoura Hills solves a specific problem: homeowners who want rental income or multigenerational space without building new square footage in a fire-hazard zone where detached construction faces strict siting limits. The 1970s-1990s housing stock here offers substantial interior volume, attached garages with conversion potential, and existing utility stubs that can be extended more cheaply than new trenching across hillside lots. We handle Junior ADU & Interior Conversion as a single contract covering design, permitting, and build.
Room-to-ADU Conversion
Signs you need it
You have a ground-floor bedroom or den with exterior access, a window that meets egress requirements, and a homeowner looking to keep the main house intact while adding a rental unit.
What it costs in Agoura Hills
Room-to-ADU conversions in Agoura Hills typically run $85,000-$140,000 all-in, including fire-hardening of shared walls where the unit attaches to the main structure.
How we do it
We verify the existing space meets Junior ADU size limits, design a separate kitchen and bath layout, prepare the permit set with LA County’s WUI overlay, and build to the documented drawings under our 365-Day Done Right Promise.
Above-Garage ADU
Signs you need it
Your two-car garage has unfinished space above with adequate headroom, and the foundation and framing can handle residential loads without full reconstruction.
What it costs in Agoura Hills
Above-garage ADUs in Agoura Hills typically run $120,000-$165,000, with fire-resistant stair enclosures and one-hour separation between garage and living space adding to base construction.
How we do it
We assess the existing structure for load capacity, design a fire-separated stair and entry, extend utilities from the main house, and deliver a permit set that satisfies both state ADU law and LA County’s fire-resistive requirements.
What Junior ADU & Interior Conversion Costs in Agoura Hills
| Item | Typical range in Agoura Hills |
|---|---|
| Room-to-ADU conversion | $85,000 - $140,000 |
| Above-garage ADU | $120,000 - $165,000 |
| Interior JADU (existing space, no structural change) | $75,000 - $110,000 |
Can a Junior ADU share utilities with the main house in Agoura Hills?
Yes, state law allows Junior ADUs to share utility meters with the primary residence, though we recommend separate sub-meters for rental management. LA County will verify the existing service capacity can handle the additional load during plan check.
Does fire-hardening apply to interior conversions too?
Yes, any new opening or changed use in a Very High FHSZ triggers Chapter 7A requirements for exterior walls and openings, even when you’re not adding square footage. We identify these triggers during design so they don’t surprise you at permit.
ADU Site Prep & Utilities in Agoura Hills
ADU Site Prep & Utilities in Agoura Hills addresses the hidden work that derails projects: original electrical panels from the 1980s that can’t handle a second dwelling, slab-on-grade foundations that need seismic retrofit, and utility trenches that must cross steep, fire-hardened terrain. We bundle this work into the same single contract as design and build, so no subcontractor can point elsewhere when grading or trenching hits Calabasas district inspection requirements. ADU Site Prep & Utilities is priced upfront, not discovered later.
Electrical Panel Upgrade
Signs you need it
Your existing panel is 100-amp service from the original build, or you’re adding electric HVAC, EV charging, or a second kitchen that pushes demand past capacity.
What it costs in Agoura Hills
Electrical panel upgrades in Agoura Hills typically run $8,500-$18,000, including trenching to Southern California Edison standards and permit coordination through LA County.
How we do it
We verify load calculations against your ADU plans, specify the new panel and service size, pull the permit, and coordinate SCE inspection so your ADU electrical passes at rough.
Foundation & Grading
Signs you need it
Your garage slab is 4 inches thick with no footing, or you’re building detached on a hillside lot where cut-and-fill requires engineered grading plans.
What it costs in Agoura Hills
Foundation and grading work in Agoura Hills typically runs $15,000-$45,000, with hillside lots and fire-hardened access roads pushing toward the upper end.
How we do it
We survey existing conditions, engage a soils engineer where required by LA County, prepare the grading plan, and build to the documented foundation design with photo records at each inspection hold.
What ADU Site Prep & Utilities Costs in Agoura Hills
| Item | Typical range in Agoura Hills |
|---|---|
| Electrical panel upgrade | $8,500 - $18,000 |
| Foundation & grading | $15,000 - $45,000 |
| Plumbing lateral extension | $12,000 - $28,000 |
Will LA County require a soils report for my hillside lot?
Most sloped parcels in Agoura Hills trigger a geotechnical report under LA County’s grading ordinance, especially where cut exceeds 5 feet or fill exceeds 3 feet. We flag this during our initial site assessment and include it in your written price.
Can utility trenching cross my defensible space zone?
Yes, but we coordinate the trench route with your final landscaping plan so hardscape and irrigation restoration comply with the 100-foot clearance requirement. County fire inspectors verify this at final.
Brands We Service in Agoura Hills
We specify and coordinate prefab and modular systems from Abodu, Cover, and James Hardie within our single-contract model. Parts and assemblies are ordered to Agoura Hills jobs with lead times built into the project schedule, not treated as surprises. See our brands for full specifications.
Pricing for ADU in Agoura Hills, CA
| Service | Typical range in Agoura Hills |
|---|---|
| Room-to-ADU conversion | $85,000 - $140,000 |
| Above-garage ADU | $120,000 - $165,000 |
| Interior JADU | $75,000 - $110,000 |
| Electrical panel upgrade | $8,500 - $18,000 |
| Foundation & grading | $15,000 - $45,000 |
| Plumbing lateral extension | $12,000 - $28,000 |
| Gas line extension | $6,000 - $14,000 |
| Landscaping & hardscape (fire-compliant) | $8,000 - $22,000 |
Three factors push Agoura Hills prices above flatland neighbors: Chapter 7A fire-hardening materials and detailing, LA County’s WUI compliance review adding plan-check rounds, and hillside terrain requiring engineered grading. Under Haven Standard Clause 1, your written price is locked before any work begins. No change orders for conditions we should have found.
Neighborhoods We Serve in Agoura Hills
We work across Agoura Hills from the canyon edges to the valley floor. Scheduling and dispatch are coordinated from our Los Angeles office; crews serve these neighborhoods with same-week site visits available.
- Old Agoura
- Malibu Junction
- Forest Cove
- Agoura Hills East
- Reyes Adobe
Service Area - Cities Near Agoura Hills
Our crews work throughout the western San Fernando Valley and Conejo Valley corridor. We regularly permit projects through neighboring jurisdictions and understand how each city’s requirements differ from LA County’s Calabasas district office. We also serve Westlake Village, CA, Oak Park, CA, Calabasas, CA, and Thousand Oaks, CA.
Serving Agoura Hills, CA - Our Local Coverage Area
We’re based in the Agoura 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 About ADU in Agoura Hills
Plan check typically runs 8-14 weeks for ADUs requiring WUI compliance review, compared to 4-8 weeks in city-run departments. We submit a complete permit set with the fire-resistive construction compliance report included to avoid the first-round rejection that adds 3-4 weeks.
State law limits HOA prohibition of ADUs, but design review committees can impose aesthetic requirements. We review your CC&Rs during our initial assessment and design to comply where possible, documenting any conflict for your legal review.
LA County assigns a separate APN or sub-address for most ADUs at final inspection, which you’ll need for utility accounts and rental agreements. We coordinate this as part of our permit management, not as an afterthought.
Call (805) 301-9518 to schedule your free estimate. Every project receives a written price before any work begins, per Haven Standard Clause 1.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Agoura Hills Customers Say
"Detached unit in the back garden. Good design, good build quality, and the cost changes were documented and agreed in advance."
- Stefan B."Every allowance was itemised at the start, so the finish selections did not turn into a surprise at the end."
- Benedict H."The permit set and the build were one contract with one number. Our neighbours used two firms and spent a year watching them blame each other."
- Helena V.