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ADU construction in Woodland Hills typically costs between $90,000 and $220,000, with most homeowners landing around $150,000 for a 600 – 800 sq ft unit. The final number depends on size, site conditions, and finish level. A basic garage conversion starts near the bottom of that range, while a detached two-bedroom ADU with a full kitchen and hillside foundation work runs toward the top.
Key Takeaways
- Typical range: $90,000 – $220,000 for a complete ADU in Woodland Hills
- Cost per square foot: $250 – $450, depending on site and finishes
- Garage conversions run $30,000 – $80,000 when the existing structure is sound
- Timeline: 6 – 14 months from design to final inspection in Los Angeles County
- Biggest cost drivers: foundation work, utility trenching, hillside grading, and kitchen/bath finishes
- Permits and fees: $8,000 – $20,000 depending on school district fees and city requirements
- Mason Remodeling provides a written price before any work starts, and every crew member is name-verified and photo-confirmed before arrival.
ADU Construction Cost Breakdown (2026)
Here’s how the numbers shake out for Woodland Hills. These are real ranges from jobs we’ve priced and built across the San Fernando Valley, not national averages. A note on why the spread is wide: hillside lots, older electrical panels, and city of Los Angeles ADU ordinances all pull the final number in different directions.
| Cost Item | Typical Range (Woodland Hills) | What It Covers |
|---|---|---|
| Design & Engineering | $8,000 – $18,000 | Architectural drawings, structural engineering, Title 24 energy calcs, soil reports if needed |
| Permits & City Fees | $8,000 – $20,000 | LA Department of Building & Safety fees, school district fees, utility connection fees |
| Site Prep & Foundation | $15,000 – $45,000 | Grading, excavation, retaining walls if the lot slopes, concrete or raised foundation |
| Framing & Shell | $25,000 – $55,000 | Wood framing, roof structure, sheathing, windows, exterior doors |
| Rough Plumbing & Electrical | $12,000 – $28,000 | Water supply, drain lines, new electrical subpanel, HVAC rough-in, trenching from main house |
| Insulation & Drywall | $8,000 – $16,000 | Exterior and interior insulation, drywall, taping, and texture |
| Interior Finishes | $18,000 – $45,000 | Flooring, paint, trim, doors, hardware, basic fixtures |
| Kitchenette / Kitchen | $14,000 – $45,000 | Depending on full kitchen vs. efficiency: cabinets, countertops, sink, appliances |
| Bathroom | $9,000 – $28,000 | Shower/tub, toilet, vanity, tile, exhaust fan, plumbing fixtures |
| Utility Hookups (separate meters) | $5,000 – $15,000 | Separate electrical meter, gas line extension, or sewer connection where required |
| Landscaping & Hardscaping | $3,500 – $11,000 | Access path, small paver patio, drainage around the ADU |
What pushes a project to the top of that range? Woodland Hills has two recurring conditions we see on nearly every hillside ADU: slope and soil. A lot off Mulholland Highway or up near Serrania Avenue often needs export of excavated earth, a taller retaining wall, and sometimes a raised foundation. Those three items alone can add $30,000 to a project that would be straightforward on a flat lot south of Ventura Boulevard.
What keeps a project toward the bottom? A garage conversion where the slab and framing are structurally sound, the electrical panel has spare capacity, and the existing roofline can be preserved. That’s the single most affordable path to a legal ADU in Woodland Hills, and it’s why garage conversions run $30,000 – $80,000 instead of the full new-construction range.
What Affects ADU Construction Pricing in Woodland Hills
Some of these are obvious. Some aren’t. All of them show up on real bids in this market.
- Lot slope and soil type. The hills north of Ventura Boulevard are beautiful and expensive to build on. Grading, drainage, and retaining walls are usually mandatory, not optional. On a sloped lot in the Woodland Hills foothills, site prep can consume 15 – 20% of the entire ADU budget.
- Detached vs. attached vs. garage conversion. A detached ADU requires a new foundation, all new utility runs, and more insulation and siding. An attached ADU shares at least one wall and often one utility line. A garage conversion reuses the slab, walls, and roof. The cost gap between a garage conversion and a detached new build is typically $60,000 – $140,000.
- Size of the unit. A 400 sq ft studio costs less than a 1,000 sq ft two-bedroom, but not proportionally less. The site prep, permit fees, and design work stay relatively fixed. The marginal cost per additional square foot in Woodland Hills runs $200 – $350 once you’re past the minimum build.
- Utility capacity and separate metering. Many homes in the older sections of Woodland Hills, especially south of the 101 near Shoup Avenue and Canoga Avenue, have 100-amp panels that are already at or near capacity. Adding a subpanel or upgrading to 200 amps runs $3,000 – $8,000. LADWP and SoCalGas connection fees add more.
- Finish level. A Home Depot stock vanity and a Moen faucet versus a custom walnut vanity and imported tile can move the interior finish budget by $20,000 or more. We quote both ways: a written price for a solid, durable tenant-ready finish, and a written price for elevated custom work. Our cabinet and countertop partnerships with KraftMaid, Wellborn, Cambria, and Silestone mean we can give you real pricing on upgraded materials without the markup games.
- Fire zone requirements. Parts of Woodland Hills south of the Santa Monica Mountains Conservancy touch into very high fire hazard severity zones. That can trigger a requirement for fire-rated siding, dual-pane tempered windows, upgraded sprinklers, and defensible-space landscaping. Those items add between $5,000 and $15,000 depending on the specific parcel.
Garage Conversion vs. Detached ADU: A Quick Cost Comparison
Homeowners who already have a two-car garage in Woodland Hills save the cost of a new foundation, framing, and roof. The trade-off is ceiling height, light, and sometimes awkward plumbing access. Here’s the side-by-side.
| Factor | Garage Conversion | Detached New Build |
|---|---|---|
| Typical total cost | $30,000 – $80,000 | $90,000 – $220,000 |
| Construction timeline | 4 – 8 months | 8 – 14 months |
| Foundation | Reuse existing slab (if engineered and sound) | New foundation required |
| Utility work | Tap existing lines; may still need panel upgrade | New trenching and utility runs |
| Ceiling height | Often 7 ft or less; sometimes needs roof raising | Full 8 – 9 ft ceilings standard |
| Floor plan | Constrained by existing garage footprint | Open, designed to suit |
The single most important question before converting a garage in Woodland Hills is whether the existing slab is thick enough and properly reinforced. Some 1950s-era garages in the Walnut Acres neighborhood meet today’s code with no issue. Others, especially those built as non-habitable space with no moisture barrier, require a new slab, which erases a chunk of the savings. An engineer’s inspection before you commit is worth every dollar.
What New California ADU Laws Mean for Your Cost
California’s ADU laws changed in 2020 and again in 2023, and Los Angeles County has pushed further with local streamlining. The practical upshot for Woodland Hills homeowners: you can build an ADU on almost any single-family lot, the city must approve or deny your permit application within 60 days, and owner-occupancy is no longer required. That last point matters for cost – you can build with the intent to rent from day one, which changes the return-on-investment math completely.
Senate Bill 9 also allows lot splits and duplexes on single-family lots, and some Woodland Hills homeowners combine an ADU with an SB 9 unit for two rentable structures. That’s beyond this pricing guide, but it’s worth knowing the option exists when you’re planning your budget.
One local note: the City of Los Angeles waives certain utility connection fees for ADUs under 750 sq ft. Depends on the exact parcel and the utility provider. Our estimator checks these on every bid so the written price we give you reflects actual, current fees – not a guess.
How to Save on ADU Construction in Woodland Hills
The right way to save is to make deliberate choices early, not to strip away quality at the end. Here’s what actually works in this market.
- Convert the garage if it’s structurally viable. This is the single biggest lever in Woodland Hills. If the slab is sound and the roofline works, you can cut six figures off a detached ADU budget. Get an engineer’s opinion. If the verdict is “no,” don’t fight it – a failing slab is a safety issue and a code violation, not a bargaining chip.
- Keep the footprint under 750 sq ft where possible. The city’s utility-fee waivers and reduced school-district fees are tied to this threshold. It’s not a savings on construction labor, but it’s real money on the permit side – sometimes $5,000 – $10,000.
- Choose the kitchen level honestly. A full kitchen with a Kohler sink, stone counters, and a 30-inch range is $14,000 – $45,000. A kitchenette with a refrigerator, microwave, and two-burner cooktop can be $8,000 – $15,000. Both are legal. Both rent. The tenant you’re targeting should decide this, not the marketing photos you saw on Instagram.
- Design on a rectangle. Every corner, bump-out, and angle adds framing time, siding cuts, and roof complexity. A simple rectangular ADU with a shed or gable roof costs less to build and less to maintain. The savings are real: $8,000 – $20,000 on a typical 600 sq ft unit.
- Get a written quote before you commit. Not a verbal estimate. A written price. Verbal numbers in this industry move. Mason Remodeling delivers a written price on every ADU project before any work starts, and that’s not a negotiation point – it’s how we’ve operated since 2004. Call (831) 290-6866 and we’ll walk your lot, check your panel, and give you a number you can bank on.
Common ADU Construction Questions, Answered with Real Numbers
How much does a 1-bedroom ADU cost in Woodland Hills?
A detached 1-bedroom ADU of about 500 – 600 sq ft typically runs $115,000 – $180,000. An attached 1-bedroom conversion runs $80,000 – $140,000. A garage conversion to a 1-bedroom runs $45,000 – $75,000 when the existing structure is sound. These ranges assume standard finishes: shower-over-tub or walk-in shower, basic kitchen, LVT or tile flooring.
How much does a 2-bedroom ADU cost in Woodland Hills?
A detached 2-bedroom ADU of 800 – 1,000 sq ft typically runs $180,000 – $220,000 and can exceed that on hillside lots with significant grading. Two bedrooms require more square footage, which requires more foundation, more roof, more everything. On a flat lot with good soil, $180,000 – $200,000 is a realistic budget for a well-built unit with a modest finish package.
Is it cheaper to build an ADU or buy a house in Woodland Hills?
Building an ADU is dramatically cheaper. The median home price in Woodland Hills runs well over $1 million. A $150,000 ADU adds rental income and square footage without a new mortgage on the land. It’s not a close comparison. The fair question isn’t “ADU vs. new house” – it’s “ADU vs. updating my current house.” And if you need rental income or a space for family, the ADU wins on return.
How long does ADU construction take in Woodland Hills?
Plan on 6 – 14 months from design to final inspection. Design and permitting run 2 – 4 months. Construction runs 4 – 10 months depending on whether it’s a conversion or new build. Weather delays are rare; inspector scheduling and utility work are the usual bottlenecks in LA County. A garage conversion often finishes in 6 – 8 months. A detached hillside build can push past 12.
Do I need a permit for an ADU in Woodland Hills?
Yes. In the City of Los Angeles, every ADU requires building permits, and most require some level of planning review even though the state has streamlined approval. Unpermitted ADUs are illegal to rent, often unsafe, and can block a future home sale. A permitted ADU built to current code is the only version that will hold its value. The residential construction work we do at Mason Remodeling is always permitted and inspected.
Can an ADU add value to my Woodland Hills home?
Yes. A legal, permitted ADU typically adds $150,000 – $300,000 to the resale value of a Woodland Hills property, with rental income and multi-generational flexibility being the primary drivers. In this market, appraisers now treat an ADU as a legitimate income-producing improvement, not an oddity. It’s one of the highest-return construction projects a homeowner can take on in the San Fernando Valley.
Is garage conversion cheaper than building a new ADU?
Yes, by a wide margin. A garage conversion in Woodland Hills runs $30,000 – $80,000 when the existing structure is reusable. A detached new-build ADU runs $90,000 – $220,000. The gap exists because a conversion reuses the slab, framing, and roof. But only an engineer’s inspection can tell you whether your garage is actually reusable. Plenty of garages in the Valley were built as non-habitable storage space with thin slabs and zero moisture protection. If yours needs a new slab, the savings shrink by $10,000 – $20,000.
Why the Builder You Choose Changes the Price
ADU construction in Woodland Hills is a six-figure commitment. The difference between a good build and a bad one isn’t visible in the first year. It shows up in year three: the door that binds, the window that leaks, the electrical panel that trips. Here’s how we price and operate, because you should know before you call anyone.
Every Mason Remodeling ADU project starts with a written price, delivered before any tools are unpacked. Not a verbal estimate that grows. Not a “we’ll see how it goes.” A written number. If the work isn’t right within 365 days of completion, the 365-Day Done Right Promise means we fix it at no cost to you. That’s a written guarantee with stated coverage and stated exclusions – not vague language.
Before any crew member steps onto your property, you get their name and photo. At the door, they carry a photo ID badge and arrive in a clean marked uniform. That’s the Threshold Standard, and it applies to every visit, every time. It matters if you’re often home alone during construction, if you have kids in the house, or if the idea of opening your door to an unvetted stranger makes you pause. It should.
Isaac Pruett leads our Woodland Hills team, and every project is handled under his direct oversight. Since 2004, Mason Remodeling has operated as part of the Threshold Group family of home-service companies, and we’ve held to the same threshold on every job: who is coming, what it costs, what is guaranteed.
The most useful first step here in Woodland Hills is a conversation. Call (831) 290-6866 – a live person answers, 24/7, including weekends and holidays. We’ll talk through your lot, your panel, your goals, and whether a conversion or new build fits. Then we’ll give you a written price. That’s the only way to know what your specific ADU costs. Estimates are free, and there’s no obligation. You can also visit our home page or read more about ADU Construction in Woodland Hills to understand the full process.
FAQs – ADU Construction Cost in Woodland Hills
What is the average cost of an ADU in Woodland Hills?
The average ADU in Woodland Hills runs $90,000 – $220,000, with most projects landing around $150,000 for a detached unit of 600 – 800 sq ft. Garage conversions average $45,000 – $70,000 when the existing structure is viable. Call (831) 290-6866 for a written price on your specific lot – estimates are free.
How much does an attached ADU cost vs. a detached ADU?
An attached ADU in Woodland Hills runs $80,000 – $140,000. A detached ADU runs $90,000 – $220,000. The difference comes down to foundation and utility trenching. Attached units share at least one wall and typically one utility line. Detached units carry all four walls, a separate foundation, and new trenching from the main house to the unit. If you’re working with a lot that has a natural landing spot against the main structure, attached is usually cheaper.
What hidden costs should I expect with an ADU in Woodland Hills?
Expect $8,000 – $20,000 in permits and city fees that homeowners rarely see coming: LA Department of Building & Safety fees, school district fees, LADWP or SoCalGas connection charges, and possible sewer lateral work. Add $3,000 – $8,000 if your electrical panel needs upgrading, and $5,000 – $15,000 if the lot is sloped and needs retaining walls or drainage. A written quote from a builder who knows this market should include these line items. Call (831) 290-6866 and ours will.
Can you build an ADU in Woodland Hills for under $100,000?
Yes, but only in specific scenarios. A garage conversion with a sound slab and existing panel capacity can run $45,000 – $80,000. A small attached studio of 400 sq ft on a flat lot with simple finishes can sometimes land near $90,000. A detached new-build ADU under $100,000 is rare in Woodland Hills and almost always involves compromises on size, finishes, or both. If budget is your top concern, a garage conversion is the path.
How do I get an exact ADU construction quote in Woodland Hills?
Call (831) 290-6866. Mason Remodeling walks your lot, checks your existing utilities and slab condition, and delivers a written price before any work begins. It’s the only way to move from a range to a real number – and it’s free.
Written by Isaac Pruett, Owner at Mason Remodeling Co Woodland Hills, serving Woodland Hills since 2004.
Pricing reflects the Woodland Hills market as of 2026. Mason Remodeling Co Woodland Hills offers free estimates – call (831) 290-6866.
What Our Customers Say
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