Licensed, bonded & insured · CSLB #996419 Los Angeles · Ventura · Santa Barbara · Riverside
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Southern California ADU builders & general contractors

Know what it costs before you call.

We publish real price ranges for every job we take on, along with the things that change the number. Find out what your ADU, roof or renovation costs without sitting through a sales visit.

Get My Price Call (714) 981-4538
  • Licensed & bonded
  • Fully insured
  • We pull every permit
  • Itemized bids

What are you thinking about building?

Typical price range in your area.

Most homeowners pay between

What changes the price

    Get a price for my home

    Takes about a minute. No phone number needed.

    Three ways to get your number

    Whichever suits you. All three end with a real price, not a callback.

    Price it online

    Describe the project in your own words and see a real range in about a minute. No phone number needed.

    Get My Price

    Talk it through

    Call and speak to someone who builds these, not a call centre. We'll give you a range on the phone.

    Call (714) 981-4538

    Book a walkthrough

    We come out, measure, and turn the range into a fixed, itemized number you can hold us to.

    Book a visit

    What an ADU costs in California

    An ADU is the highest-return thing most homeowners can build, and the hardest to get a straight price on. Here is ours, by unit type, before you call anyone.

    Type of ADUTypical sizeTypical rangeTimeline
    Junior ADU (JADU)Up to 500 sq ft $90,000 – $150,0003–5 months
    Garage conversion350–500 sq ft $95,000 – $165,0004–6 months
    Prefab / modular400–800 sq ft $150,000 – $280,0005–8 months
    Attached ADU500–800 sq ft $170,000 – $290,0006–9 months
    Detached ADU600–1,000 sq ft $220,000 – $385,0007–11 months
    Completed detached accessory dwelling unit built by Northcraft Builders in Simi Valley, California

    What moves the number

    • Whether utilities reach without upgrading your electrical service
    • How easily equipment gets into the backyard
    • Slope, drainage, and what the soils report says
    • Whether your city requires design review
    • The finish level you choose inside
    See full ADU pricing
    B 1 C 12 6 TOP PLATE FINISHED FLOOR 8'-0" 14'-9" 25'-0" FINISHED GRADE 1 2 5 6 FRONT ELEVATION Gable end · entry D E F D TOP PLATE FINISHED FLOOR 8'-0" 30'-0" 3 4 7 8 9 SIDE ELEVATION Eave wall · utilities KEYNOTES 1 Class A composition shingle over synthetic underlayment 2 7/8" three-coat stucco over two layers Grade D paper 3 Wood roof trusses at 24" on centre 4 R-38 ceiling / R-21 wall, Title 24 compliant 5 Screened gable-end attic vent, per code 6 2x6 fascia with continuous vented soffit 7 Dual-glazed vinyl windows, per Title 24 8 Sub-panel from main service, load calc req. 9 Slab-on-grade, continuous footing per structural NORTHCRAFT BUILDERS · TYPICAL DETACHED ADU ILLUSTRATIVE — NOT FOR CONSTRUCTION CONDITIONED AREA 750 SQ FT FOOTPRINT 25'-0" × 30'-0" OCCUPANCY 2 BED / 1 BATH PLATE HEIGHT 8'-0" ROOF PITCH 6:12 OVERALL HEIGHT 14'-9" ABOVE GRADE
    A typical detached ADU we build. 750 sq ft on a 25′ × 30′ footprint, 8′ plate, 6:12 roof, 14′-9″ to the ridge — under the 16-foot height limit most California cities apply to detached units.

    We handle the ADU from the first sketch to final sign-off

    • Feasibility check on your actual parcel before you spend a dollar on design
    • Plans, structural engineering and Title 24 handled in-house
    • We submit the permit and answer every correction letter
    • One site lead, a weekly update, and a schedule you can plan around
    See how ADUs work
    Northcraft Builders crew framing a detached ADU in Southern California

    Every service, with the price attached

    Each one has its own page with a full price breakdown, the permit process for your city, and a realistic timeline.

    Detached accessory dwelling unit with its own entrance and private patio

    ADU Construction

    $220,000 – $385,000

    Detached units, attached builds and junior ADUs, permitted end to end.

    7–11 monthsPermit required
    New tile roof installed on a single-storey Southern California home

    Roof Replacement

    $18,000 – $42,000

    Full tear-off and rebuild, from composition shingle to tile and metal.

    3–6 days on sitePermit required
    Two-car garage converted into a permitted junior accessory dwelling unit

    Garage Conversion

    $95,000 – $165,000

    Turning an existing garage into permitted, legal living space.

    4–6 monthsPermit required
    Renovated open-plan living and kitchen area after a whole-home remodel

    Whole-Home Renovation

    $180,000 – $550,000

    Full interior rebuilds, including moving walls and updating aging systems.

    6–12 monthsPermit required
    Finished gunite swimming pool with surrounding concrete decking

    Swimming Pools

    $85,000 – $160,000

    Gunite pools, spas and decking, including the safety barrier your city requires.

    3–5 monthsPermit required
    Covered patio and timber deck built onto the rear elevation of a home

    Decks & Patios

    $18,000 – $55,000

    Decks, patio covers, pergolas and outdoor kitchens built to last outdoors.

    2–5 weeksDepends on size

    California ADU law, in plain English

    State law sets the floor for ADUs everywhere in California, and your city fills in the rest. Knowing which is which is most of the battle.

    Approval is ministerial

    State law generally requires cities to approve a conforming ADU application without a public hearing or discretionary review. Your neighbours don't get a vote on a compliant unit.

    There's a review clock

    Cities have to act on a complete ADU application inside a set window rather than letting it sit.

    Parking rules are limited

    State law restricts when a city can require parking for an ADU, and restricts requiring replacement parking when a garage is converted.

    Owner-occupancy

    Whether you have to live on the property has changed more than once in recent years, and it differs between ADUs and junior ADUs.

    Impact fees and size

    Smaller units are treated differently from larger ones on impact fees, and there are statutory size floors a city cannot zone below.

    What your city still controls

    Objective design standards, height and setback limits, fire-zone requirements, historic overlays, and how your utility handles a new meter. This is where projects actually get stuck, and it differs across all 134 cities we serve.

    We don't publish statute numbers we haven't checked. California ADU law has changed nearly every year since 2017, and city ordinances change on their own schedule. Every figure on our city pages carries a source and the date we verified it. Requirements vary by jurisdiction — confirm current rules with your building department before relying on anything you read here, including this.

    Read the full ADU law guide What is an ADU?

    Four counties. Every city.

    Choose your county below. Every city has its own page with that city's ADU rules and permit process on it.

    Describe your project. Get a price.

    No long form to fill out. Tell us what you're dealing with the way you'd say it out loud, and we'll do the rest.

    1

    You describe it

    In your own words. Whatever you happen to know about it is enough to get started.

    "Simi Valley, 6,500 sq ft lot, I want a two-bedroom ADU in the back for my mother. No idea if it fits."

    2

    We work out the scope

    Your description becomes a real scope of work. We'll only ask one follow-up question, and only if it genuinely changes the price.

    Detached ADU · roughly 750 sq ft · new foundation · separate utility drop · permit required

    3

    You see the price first

    The number comes before we ask for anything. If it's not the year for it, take the number and go. That's the whole point.

    Your range: $248,000 – $341,000
    Based on Simi Valley pricing

    See the difference for yourself

    Drag the handle across the photo. Every project we finish gets its own page — what the homeowner wanted, what we found once we opened it up, and what it cost.

    Detached 760 square foot ADU after construction, Simi Valley, California
    Rear yard before ADU construction, photographed from the same position
    BeforeAfter
    ↔

    Drag the circle left and right to compare

    Detached 760 sq ft ADU on a standard lot

    City
    Simi Valley
    Size
    760 sq ft, 2 bed
    Duration
    9 months
    Permit
    City of Simi Valley
    Cost
    $255,000 – $290,000
    See all our projects

    Three things most contractors won't do

    Not because they can't. Because doing them out in the open makes it harder to pad a bid.

    Northcraft BuildersMost contractors
    Pricing Real ranges published on every page, with the things that change them spelled out. You can rule us out on budget without ever speaking to us. "Call us for a quote."
    Permits We submit and we handle corrections on every job that needs one. We know the counter, the portal, and how long plan check is actually taking in your city. "You can pull it yourself as the homeowner."
    The bid Itemized by trade and material, so you can honestly compare us against anyone else you're talking to. One number on one page.
    Reaching us A named site lead, a weekly update, and you always know who is showing up tomorrow. Voicemail, once the deposit clears.
    Northcraft Builders site lead reviewing plans on an active job site

    Why homeowners pick us

    Licensed and accountable

    CSLB #996419, bonded and insured. Verify it yourself at cslb.ca.gov before you sign anything.

    Prices in the open

    Real ranges on every page and an itemized bid at the end. Nothing hidden behind a callback.

    Permit-fluent

    We know the counter, the portal and the plan-check reality in all 134 cities we cover.

    One named site lead

    The same person from walkthrough to sign-off, with a weekly update you don't have to chase.

    Get a real range in about a minute

    Describe it in your own words. You'll see a number before we ask you for anything at all.

    Get My Price Call us

    How a job actually runs

    Eight steps, in this order, every time. You'll always know exactly where things stand.

    1. Walkthrough

      We come out, measure, and tell you what's realistic on your budget before anyone commits.

    2. Design & selections

      Drawings where the job needs them, and materials priced as you choose them.

    3. Itemized estimate

      Broken out by trade and material, so you can compare it against anyone.

    4. Contract & schedule

      Fixed scope, payments tied to milestones, and a start date in writing.

    5. Permit & plan check

      We submit it and we handle the corrections. You never sit at a counter.

    6. We build

      A named site lead, a weekly update, and you know who's arriving tomorrow.

    7. Punch list

      We walk the job with you, fix everything on your list, and hand over the sign-off.

    8. Warranty

      Workmanship coverage in writing, plus manufacturer warranties passed through.

    Worth reading before you hire anyone

    What is an ADU?

    The four types, what each one can legally be, and which makes sense on a normal lot.

    Read the guide

    California ADU law in plain English

    What the state guarantees you, what your city can still say no to, and where they collide.

    Read the guide

    What an ADU actually costs to build

    Where the money goes, and the five things that account for most of the spread.

    Read the guide

    Questions, answered

    Straight answers, without a sales call to get them.

    How much does an ADU cost to build? +
    Most detached ADUs in our area run $220,000 to $385,000 for a 600–1,000 sq ft unit. A garage conversion starts closer to $95,000, and a junior ADU inside the existing house is the cheapest path of all.
    Can I build an ADU on my lot? +
    Usually yes. State law makes ADUs allowable on most single-family and multifamily lots in California. What varies is size, height, setbacks and design standards, and that's set by your city. We check your specific parcel before you spend anything on design.
    How long does an ADU take? +
    Seven to eleven months for a detached unit, start to final inspection. Design and plan check take up a bigger share of that than most people expect.
    Do you pull the permit, or do I? +
    We do, on every job that needs one. We submit the plans and handle the correction letters. You never sit at a counter.
    Which areas do you actually cover? +
    Los Angeles, Ventura, Santa Barbara and Riverside counties, out of our office in Simi Valley. Pick your county in the coverage section above to find your city.
    Are you licensed and insured? +
    Yes. Northcraft Builders holds California contractor license #996419 and carries a contractor's bond and general liability insurance. You can verify the license yourself at cslb.ca.gov.
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