How Much Does an ADU Cost in Los Angeles?

The honest 2026 breakdown: LA ADUs run about $300–$450 per square foot and $150k–$400k all-in — but the California median is ~$150k and 71% cost under $200k. Here's exactly where the money goes, by ADU type. Then we'll connect you with a vetted, CSLB-licensed LA builder.

We match you with vetted, California-licensed ADU builders in your area — no guesswork, no cold-calling contractors.

What an ADU actually costs in LA.

If you've been quoted scary six-figure numbers, you're not wrong — but the picture is more nuanced than the sticker shock suggests.

$300–$450

per square foot (LA custom build, 2026)

$150k–$400k+

typical all-in cost, depending on type & size

~10–15%

of budget goes to utilities & site work — the most under-estimated line item

Reframe the sticker shock: the statewide median ADU cost is about $150,000 (~$250/sq ft), and 71% of California ADUs cost under $200,000, per the UC Berkeley Terner Center owner survey. The LA premium ($300–$450/sq ft) is real — but most ADUs are not the $650k horror stories you read about. Smart scoping, the right ADU type, and a builder who knows local LADBS rules keep you on the right side of that median.

Cost breakdown by build type.

The single biggest lever on your final number is which type of ADU you build. Here's how the four main paths compare in Los Angeles.

Garage Conversion

~$100k–$225k in LA · 3–6 months

The cheapest route to a legal ADU — you reuse the existing slab, walls, and roof, so you're paying mostly for systems and finishes, not structure.

• Lowest cost per square foot of any type
• Fastest timeline (clean conversions finish in 4–6 months total)
• Watch for: electrical panel upgrades, sewer tie-in, and bringing an old slab up to code

Prefab / Modular

~$180k–$350k all-in · ~6–8 months

Built in a factory and craned onto your lot. Often 10–20% cheaper on straightforward jobs — but the headline "base price" is not the final price. See our full prefab vs. custom ADU cost breakdown.

• Faster on-site install (weeks, not months)
• Base price ≠ final price: site work, utilities, foundation, and permit fees are usually add-ons (often $40k–$60k extra)
• NOT "done in a month" — permitting, sitework, and factory queues still apply

Custom Stick-Built (Detached)

~$200k–$450k all-in · LA avg $300–$350/sq ft

A fully custom unit built on-site. Maximum design flexibility — and the type most likely to see cost overruns if scoped loosely.

• Total control over layout, finishes, and size
• Highest cost and longest timeline of the four
• Best paired with a fixed-price contract to avoid change-order creep

Attached ADU

Generally cheaper than detached

Added onto your existing home, sharing a wall. Often less expensive than a standalone detached unit because it can share structure and some utility runs.

• Can reuse part of the existing foundation and utility connections
• Good middle-ground on cost between conversion and detached
• Layout is constrained by your home's existing footprint

The full all-in cost stack.

"Cost to build" is only part of the story. Here's the complete picture for a typical LA detached ADU, so nothing surprises you later.

The 750-sq-ft sweet spot: impact-fee exemption

Under California state law (SB 13), ADUs under 750 square feet are exempt from local development impact fees. On many LA projects that's thousands of dollars erased from the budget — which is exactly why so many ADUs land right around that size. A builder who knows the rule can scope your unit to capture the exemption.

Three things competitors won't tell you.

The "$40,000 CalHFA grant" is currently paused

The CalHFA $40,000 ADU Grant covered pre-development costs — but the last round was fully allocated in December 2023 and the program is currently paused and out of funds, with no confirmed relaunch. Many builder pages still advertise it as live. It may reopen if the state appropriates new money, so check the official CalHFA ADU page before counting on it. (See our ADU financing guide for the paths that actually work today.)

The "60-day permit" is the law, not your real timeline

California statute requires the city to approve or deny a complete ADU application within 60 days. In practice, that clock is widely missed on custom builds — a real LA custom permit takes 3–6 months, with the correction-loop being the painful part. Pre-approved LADBS Standard Plans are the genuine fast track (often 21–30 days). Treat any builder who "guarantees a 60-day permit" with caution.

A contractor cannot legally take a big deposit up front

California law (BPC §7159.5) caps a contractor's down payment at $1,000 or 10% of the contract price, whichever is less — which means effectively $1,000 on any ADU. "Material reservation," "lumber-lock," or "pre-construction onboarding" fees that ask for tens of thousands up front are repackaged illegal deposits. Every builder in our directory is verified to operate within this cap and carries an active CSLB license you can look up yourself.

Get your personalized LA ADU cost estimate.

Answer a few quick questions about your lot and the ADU you want, and we'll send you a tailored cost range, projected rent and ROI, and an estimated payback period — built on real LA build data.

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Find out if your property even qualifies.

The smartest move isn't getting a quote — it's finding out whether your lot can support an ADU in the first place. That's free, and it takes minutes.

Step 1 — Free property qualification check. Enter your address and we'll review zoning, lot size, and setbacks, then tell you straight whether you likely qualify to build. No cost, no commitment.

Step 2 — Free on-site feasibility assessment. If it looks viable, one of our vetted, CSLB-licensed LA builders comes out to check your electrical panel, water and sewer, access, and layout — so your eventual quote is real, not a guess.

1-800-ADU-Pros is the directory and matchmaker; the licensed pro does the build. You get a pre-screened builder who knows LADBS, ZIMAS, and the local ordinance — without cold-calling a single contractor.

Who you'll be matched with.

Every builder in our directory is license-verified — we confirm an active CSLB license from public records before we list them. Here are three of the vetted, California-licensed ADU builders serving the Los Angeles area.

[

GC

Goldenline Construction

CSLB #989378 · Class B · Active ✓

Serving Woodland Hills, Encino, Sherman Oaks, Van Nuys & the West SFV. Rated 4.9★ across ~495 reviews.

](/builder/goldenline-construction)[

DH

Dwell Homes Los Angeles

CSLB #1030158 · Class B · Active ✓

Valley Village–based, building across the San Fernando Valley & greater Los Angeles.

](/builder/dwell-homes-los-angeles)[

LA CCS

LA CCS

CSLB #1047699 · Class B · Active ✓

Encino-based, serving the full San Fernando Valley, Glendale, Burbank, Pasadena & San Gabriel Valley.

](/builder/la-ccs)

ADU cost questions, answered.

How much does it cost to build an ADU in Los Angeles in 2026?

Most ADUs in Los Angeles run about $300–$450 per square foot, or roughly $150,000–$400,000+ all-in depending on size, type, and site conditions. A garage conversion is the cheapest path (around $100k–$225k in LA); a custom detached stick-built unit is the most expensive. For perspective, the statewide median ADU cost is about $150,000 and 71% cost under $200,000.

What is the cost per square foot for an ADU in Los Angeles?

In LA, ADU construction generally runs about $300–$450 per square foot for a custom detached build, with many builders quoting starting points around $350/sq ft. Garage conversions cost less per foot because the foundation, walls, and roof already exist.

How much does an ADU permit cost in Los Angeles?

LADBS plan-check and permit fees for an ADU typically total a few thousand dollars, but the full soft-cost stack — design plans, structural engineering, surveys, and utility/school fees — usually lands in the $10,000–$30,000 range. Critically, ADUs under 750 square feet are exempt from local impact fees under state law (SB 13), removing one of the largest fee line items. See our LA permit process guide for the full walkthrough.

How much does a garage conversion cost in Los Angeles?

A garage conversion ADU in LA typically costs about $100,000–$225,000 and takes 3–6 months — the most affordable way to add a legal ADU, because the existing structure, foundation, and roof are reused. Final cost depends on utility upgrades, electrical panel capacity, and how much of the existing slab and framing can be kept.

Is the $40,000 CalHFA ADU grant still available?

No. The CalHFA $40,000 ADU Grant for pre-development costs is currently paused and out of funds — the last round was fully allocated in December 2023 and there's no confirmed relaunch. It may reopen if the state appropriates new funding, so verify the current status at calhfa.ca.gov before counting on it.

Why do ADUs cost almost as much per square foot as a full house?

An ADU is a complete, independent dwelling — it needs its own kitchen, bathroom, HVAC, electrical, and often a separate sewer lateral and electric meter. Those high-cost systems are packed into a small footprint, so the per-square-foot number stays high. Site work and utility connections (often 10–15% of the budget) are the most commonly under-estimated costs.

Will building an ADU raise my property taxes in California?

Only the new ADU is reassessed — typically at about 1% of its construction value per year. Your existing home keeps its original Proposition 13 tax basis and is not reassessed because you added an ADU. This is one of the most common misconceptions among LA homeowners.

Cost and policy figures sourced from the UC Berkeley Terner Center ADU owner survey, CalHFA, the CSLB deposit-law release, and LADBS. Ranges are estimates for planning; your builder's site-specific quote is the source of truth.

Related ADU guides.

ADU Permits in LA Process, cost & timeline (2026) Can I Build an ADU? Eligibility & setback rules How to Pay for an ADU HELOC, refi, loans & the CalHFA grant Garage Conversion Costs The cheapest path to a legal ADU Legalize an Unpermitted ADU Retroactive permits under AB 2533 Browse Vetted Builders License-verified LA ADU pros