Building an ADU in West Hills costs between $120,000 and $310,000 for most projects in 2026. Garage conversions land near the low end. A detached new build on a sloped or fire-zone lot pushes past $310,000 and can reach $400,000 or more. The spread comes down to what you're starting with, your parcel's terrain, fire zone designation, and which LADBS permit track you qualify for.
West Hills falls within the City of Los Angeles boundary (ZIP codes 91304 and 91307). That means LADBS jurisdiction, not Ventura County. It also means LAUSD school fees, VHFHSZ fire zone compliance on many parcels, and a housing stock that runs heavily pre-1980.
We serve West Hills from Simi Valley, about 15 minutes north on the 118. Safeway Construction has been building ADUs throughout West Hills, Woodland Hills, and Ventura County for over 20 years. License #1066117. 5.0 stars on Google.
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ADU Types and What They Cost in West Hills
Every ADU cost discussion starts with type, because the project scope varies by a factor of three from a junior ADU to a detached build on a hillside lot.
Junior ADU (JADU): $90,000 – $130,000
A Junior ADU is carved from existing living space inside your home: a converted bedroom, a portion of a ground-floor attached garage, or a rear suite with a separate entrance. JADUs are capped at 500 sq ft under California law and must include a separate entrance, an efficiency kitchen, and a bathroom.
In West Hills, a JADU conversion on a home with plumbing and electrical already nearby runs $90,000–$105,000. If the conversion requires adding a bathroom from scratch or relocating walls, budget $110,000–$130,000. JADUs do not require a separate utility meter, eliminating $8,000–$22,000 in utility connection costs.
Garage Conversion: $120,000 – $180,000
A garage conversion is the most popular ADU type in West Hills. The existing foundation and structure reduce costs compared to new construction. Converting requires adding insulation, drywall, proper flooring, a full kitchen, a bathroom, a water heater, HVAC, natural light and egress windows, and a separate sub-panel or electrical upgrade.
Standard range: $120,000–$155,000 for a single-car conversion with standard finishes on a flat lot without fire zone complications. $155,000–$180,000 for a two-car conversion, fire zone materials, or a pre-1978 home requiring asbestos documentation and abatement.
Attached ADU: $175,000 – $265,000
An attached ADU is an addition to the primary home built to ADU standards: its own entrance, kitchen, bathroom, and address. A modest flat-lot attached ADU with standard finishes runs $175,000–$210,000. Fire zone properties or homes requiring asbestos abatement or panel upgrades push the range to $230,000–$265,000.
Detached ADU (Standard): $200,000 – $310,000
A detached ADU is a fully independent structure on your lot with its own foundation, framing, roof, mechanical systems, utility connections, and address. Most West Hills detached units run 400–800 sq ft. This is the highest-demand type for rental purposes.
Utility connections (sewer lateral, water service, and gas) run $8,000–$22,000 depending on trench distance. Trenching through an existing concrete driveway adds $3,000–$8,000. Get your number before committing to a design at SafewayQuickQuote.com.
Detached ADU (Hillside / Fire Zone): $280,000 – $400,000+
Properties in northern West Hills near the hills bordering Chatsworth face steeper grades and stronger fire zone designations. Sloped lots require engineered foundations with caissons at $1,500–$2,500 each (typically 4–8 per structure) plus grading, drainage, and retaining work adding $15,000–$35,000 in site work. Fire zone material requirements on VHFHSZ-designated parcels add $8,000–$18,000 to exterior costs.
Per-Component Cost Breakdown
This table reflects costs for a standard detached ADU (450–650 sq ft) in West Hills. Adjust each line item up or down based on your ADU type and site conditions.
| Component | Typical Cost Range |
|---|---|
| Architectural design and drawings | $4,500 – $12,000 |
| Structural engineering (if required) | $2,000 – $6,500 |
| LADBS permit fees | $3,000 – $9,500 |
| LAUSD school fee ($4.79/sq ft) | $2,150 – $4,800 |
| Foundation (slab, flat lot) | $8,000 – $18,000 |
| Foundation (caissons, hillside) | $15,000 – $35,000 |
| Framing and structural | $14,000 – $32,000 |
| Fire zone exterior materials (VHFHSZ) | $8,000 – $18,000 |
| Roofing (Class A required in VHFHSZ) | $5,000 – $14,000 |
| Windows and exterior doors | $4,500 – $12,000 |
| Electrical (including sub-panel) | $5,000 – $13,000 |
| Plumbing (full kitchen + bath) | $7,000 – $18,000 |
| Utility connections (sewer/water/gas) | $8,000 – $22,000 |
| Mini-split HVAC system | $3,500 – $8,500 |
| Insulation (Title 24 required) | $2,500 – $6,000 |
| Drywall and interior finish | $4,000 – $9,500 |
| Kitchen (cabinets, countertops, appliances) | $8,000 – $28,000 |
| Bathroom tile and fixtures | $5,500 – $16,000 |
| Flooring | $3,500 – $12,000 |
| Asbestos testing and abatement (pre-1978) | $300 – $6,500 |
| Contingency (10%) | $12,000 – $32,000 |
The LADBS Permit Process for West Hills ADUs
West Hills ADUs go through LADBS using ministerial review. California state law (AB 68, AB 881, SB 13, AB 2221) requires LADBS to approve any code-compliant ADU application on a ministerial basis. All submissions are digital-only through the LADBS online portal.
Standard plan check applies to custom ADU designs. LADBS has 60 days to complete review. In practice, first-round corrections are common. Expect 4–8 weeks for a clean submission, and up to 14–16 weeks if corrections are required. The January 2026 wildfire backlog elevated processing times through much of 2026.
Pre-approved standard plans are the faster route. LADBS maintains 20+ pre-approved ADU designs. When you use one, LADBS only reviews site-specific conditions, cutting permit issuance to 21–30 days. Pre-approved plan sets cost $1,500–$3,500 vs. $4,500–$12,000 for a custom design.
LAUSD school fee: Any ADU over 500 sq ft triggers a LAUSD school development fee of $4.79 per sq ft. A 600 sq ft unit: $2,874. An 850 sq ft unit: $4,072. Under SB 543, ADUs at or under 500 sq ft are exempt.
Pre-1978 homes: LADBS requires asbestos and lead testing documentation before issuing permits for any work on a pre-1978 structure. Testing costs $300–$700. If asbestos-containing materials are found, abatement adds $1,500–$6,000.
West Hills ADU Rental Income by Type
These estimates reflect West Hills market rents in mid-2026. West Hills draws renters from Pierce College, Woodland Hills healthcare employers, and commuters using the 118 and 101 corridors.
| ADU Type | Size | Monthly Rent |
|---|---|---|
| Junior ADU (studio) | 350–500 sq ft | $1,700 – $2,100 |
| Garage conversion (1 bed/1 bath) | 400–550 sq ft | $1,900 – $2,400 |
| Attached ADU (1 bed/1 bath) | 500–700 sq ft | $2,100 – $2,600 |
| Detached standard (1 bed/1 bath) | 500–700 sq ft | $2,200 – $2,700 |
| Detached standard (2 bed/1 bath) | 700–850 sq ft | $2,600 – $3,100 |
A detached 700 sq ft ADU generating $2,600/month produces $31,200/year in gross rental income. At a $250,000 build cost, that's roughly an 8-year payback on the construction investment before considering property value appreciation.
ROI and Property Value
ADUs in West Hills add measurable equity. A well-built 600–800 sq ft detached unit typically adds $170,000–$290,000 in property value on a home already trading at $900,000–$1.3M.
For homeowners weighing an ADU against a room addition, the ADU wins on ROI when rental income is part of the plan. A $250,000 detached ADU returning $2,400/month covers its own debt service in most HELOC or cash-out refi financing scenarios.
For a full comparison, see our West Hills ADU Permit Guide and our Room Addition Cost Guide for West Hills.
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Timeline by ADU Type
| ADU Type | Design | Permits | Construction | Total |
|---|---|---|---|---|
| JADU | 3–4 wks | 3–5 wks | 10–14 wks | 4–6 mo |
| Garage conversion | 4–6 wks | 4–8 wks | 12–18 wks | 5–8 mo |
| Attached ADU | 5–8 wks | 5–8 wks | 16–22 wks | 7–10 mo |
| Detached standard | 6–10 wks | 5–8 wks | 18–26 wks | 8–11 mo |
| Detached hillside/fire zone | 8–12 wks | 6–10 wks | 22–32 wks | 10–14 mo |
Neighborhood-Specific ADU Pricing in West Hills
Shadow Ranch
Homes built primarily between 1965 and 1985. Many still have 100-amp panels and galvanized supply lines, which may require upgrading. Factor in a panel upgrade ($2,500–$5,000) and galvanized replacement ($2,000–$4,500) as contingency items.
Detached ADU range in Shadow Ranch: $210,000–$285,000 for a standard flat-lot build.
Fallbrook / Pierce College Area
Strong rental demand from students and faculty. Larger lots with more room for a detached unit. Generally more gradual terrain keeps foundation costs lower.
Garage conversion range: $125,000–$165,000. Detached ADU range: $200,000–$270,000.
Orcutt Ranch
One of the older pockets of West Hills, with some homes from the early 1960s. More likely to carry asbestos in walls, ceilings, and floor adhesives. Budget an extra $8,000–$15,000 for older-home infrastructure unknowns.
Detached ADU range: $220,000–$310,000 once infrastructure factors are included.
Platt Village
1980s–1990s construction with generally updated infrastructure. Fewer pre-1980 concerns. Properties here are less likely to sit in the VHFHSZ, saving $8,000–$18,000 on a detached build compared to north-side parcels. Detached ADU range: $195,000–$265,000.
Financing Your West Hills ADU
| Method | How It Works | Best For |
|---|---|---|
| HELOC | Revolving credit secured by home equity | 30%+ equity, prefer flexibility |
| Cash-out refi | Refinance for more than owed, take the difference | Replacing a high-rate mortgage |
| CalHFA ADU Grant | Up to $40,000 toward pre-construction costs, no repayment | Income-qualifying homeowners |
| Construction loan | Short-term loan converting to mortgage at completion | Large detached builds |
The CalHFA ADU Grant covers up to $40,000 of pre-construction costs: design, permits, school fees, utility connection fees, and soil reports. For most West Hills homeowners with equity in the $900,000–$1.2M range, a HELOC at current rates is the most flexible option.
West Hills ADU Costs vs. Nearby Cities
| City | JADU | Garage Conv. | Detached Std. | Jurisdiction |
|---|---|---|---|---|
| West Hills | $90K–$130K | $120K–$180K | $200K–$310K | LADBS |
| Woodland Hills | $80K–$120K | $120K–$175K | $200K–$310K | LADBS |
| Calabasas | $85K–$125K | $125K–$185K | $215K–$330K | City |
| Thousand Oaks | $75K–$110K | $110K–$165K | $180K–$280K | City |
| Simi Valley | $70K–$100K | $100K–$155K | $165K–$260K | City |
West Hills and Woodland Hills track closely because both fall under LADBS jurisdiction with LAUSD school fees. We serve all five cities. See our ADU Cost Guide for Woodland Hills and ADU Cost Guide for Calabasas.
California ADU Law: What West Hills Homeowners Need to Know
AB 2221 (2023): Clarifies and expands ADU protections statewide. Limits the grounds on which local agencies can deny ADU permits. Strengthens the ministerial review requirement.
AB 1033 (2023): Allows homeowners to sell a detached ADU separately from the primary dwelling as a condominium.
SB 543 (2023): Exempts ADUs at or under 500 sq ft from school development fees. Relevant for West Hills because it avoids the LAUSD $4.79/sq ft fee on compact units.
SB 9: Allows homeowners to split a single-family lot or build a duplex in certain zones, expanding what's buildable on a West Hills parcel. For more detail, see our West Hills ADU Permit and Cost Guide.
Frequently Asked Questions
How long does an ADU take to build in West Hills?
A garage conversion typically runs 5–8 months from design to final inspection. A detached ADU runs 8–11 months. Hillside or fire zone projects add 2–3 months. The biggest variable is the LADBS permit phase: a clean first submission saves 4–8 weeks over a project that requires corrections.
Do I need a separate meter for my West Hills ADU?
California law prohibits local agencies from requiring a separate utility meter as a condition of ADU approval. You may choose to install separate meters for practical billing purposes if renting the unit. JADUs are not allowed to have separate utility meters.
Can I build an ADU in West Hills if I'm in the fire zone?
Yes. Being in the VHFHSZ does not block ADU construction. It adds exterior material requirements (Class A roofing, ember-resistant venting, tempered windows, ignition-resistant cladding) and defensible space compliance. Plan for an $8,000–$18,000 cost adder on a detached build.
What's the school fee for a West Hills ADU?
LAUSD charges $4.79 per square foot on ADUs over 500 sq ft. A 650 sq ft unit: $3,114. An 850 sq ft unit: $4,072. ADUs at or under 500 sq ft are exempt under SB 543. JADUs are always exempt.
Is a permit required for a garage conversion in West Hills?
Yes. All ADU construction in West Hills requires LADBS permits: building, plumbing, electrical, and mechanical. Unpermitted ADUs create title problems at sale and liability issues if a tenant is injured. We handle the full permit process on every project.
Does Safeway Construction serve West Hills?
We serve West Hills, Woodland Hills, Calabasas, Thousand Oaks, Moorpark, Simi Valley, and Ventura County from our base in Simi Valley. Licensed (#1066117), insured, over 20 years experience. For a quick cost range, start at SafewayQuickQuote.com.
The Bottom Line on West Hills ADU Costs
Building an ADU in West Hills is a bigger project than the national averages suggest. LADBS fees, LAUSD school fees, VHFHSZ fire zone material requirements, and the pre-1980 housing stock all add real dollars. A garage conversion at $120,000–$180,000 is still the most accessible entry point. A detached unit at $200,000–$310,000 is the highest-return option if rental income is your goal.
Start with your ballpark. Get a free AI-powered estimate at SafewayQuickQuote.com. Two minutes, no contractor visit, no sales pressure. Then call us at (805) 222-6544 when you're ready to talk specifics.
Related West Hills Resources
- West Hills ADU Permit and Cost Guide (2026) — Permits, rules, and process overview
- West Hills Remodeling Guide 2026 — Complete overview of remodeling in West Hills
- Kitchen Remodel Cost in West Hills (2026) — Pricing tiers, LADBS permit costs, neighborhood guide
- Bathroom Remodel Cost in West Hills (2026) — Per-component costs, older home considerations
- Room Addition Cost in West Hills (2026) — 4-tier pricing, LADBS process, ROI analysis
- ADU Cost in Woodland Hills (2026) — Comparable LADBS market, hillside lot pricing
- ADU Cost in Calabasas (2026) — HOA considerations, hillside premium