How much does an ADU cost in Los Angeles in 2026?

Most detached LA ADUs land between $300K and $500K all-in. Garage conversions typically run $160K–$260K. We hand over a one-page feasibility note with a real number before any contract.

Do you handle LADBS permits?

Yes — full plan set, structural calcs, Title 24 energy compliance, and the LADBS back-and-forth so the homeowner only signs at the milestones.

How much does an ADU cost in the Bay Area in 2026?

Most detached Bay Area ADUs land between $380K and $620K all-in — roughly 15–25% above LA due to labor, sewer/water tie-in, and hillside access. Garage conversions typically run $190K–$300K.

Which Bay Area city is fastest for ADU permits?

San Jose is the fastest in the Bay — the pre-approved plan program can drop the permit window under 8 weeks for standard lots. Oakland and Fremont are next; SF DBI is the slowest at 5–8 months.

California ADU Builder.

We design, permit, and build accessory dwelling units across Greater Los Angeles — detached backyard ADUs, attached additions, garage conversions, and JADUs. One team, one number to call, from the first feasibility walk through the final LADBS inspection.

We build ADUs across the Bay — San Francisco, Oakland, San Jose, Fremont, Walnut Creek, Palo Alto, Sunnyvale, and the Peninsula. Every Bay city has its own permit rhythm, water utility, and hillside rules; we run the feasibility, the city back-and-forth, and the construction so the homeowner only signs at the milestones.

Los Angeles

$300K – $500K all-in

Lot access, slab condition, panel upgrade, and finish level move the number most. Pre-approved plans trim 5–10%.

Timeline — Plan on 3–5 months for design + LADBS permit, then 4–6 months on-site for an 800–1,000 sqft detached ADU.

Los Angeles ADU Builder →

San Francisco Bay Area

$380K – $620K all-in

Hillside access, sewer lateral upgrade, EBMUD/SFPUC tie-in, and city review length drive the band. Costs run 15–25% higher than LA.

Timeline — Plan on 4–7 months for design + city permit (8 months for SF), then 5–7 months on-site for an 800–1,000 sqft detached ADU.

San Francisco Bay Area ADU Builder →

What we actually build inside adu builder.

Every component below has its own field page — materials, California code notes, cost bands, common mistakes, and FAQ.

Scope — what we deliver.

Site walk, feasibility note, and zoning / LAR1 / RD overlay check
Full architectural plan set, structural, MEP, Title 24 energy
LADBS or local-city permit submittal and back-and-forth
Foundation, framing, MEP rough, finishes, landscape tie-in
Final inspection, certificate of occupancy, and warranty

Permits look different in LA vs the Bay.

Los Angeles — permit notes

LADBS pre-approved ADU plans can compress the permit window to 4–6 weeks when the lot fits a standard footprint.
Hillside Ordinance (HCR), HPOZ, and Coastal Zone overlays add review time — we flag them in the feasibility note before contracting.
LADWP service-line upgrades (200A panel, water lateral) are the most common cost surprise; we price them in upfront.
Most LA jurisdictions allow detached ADUs up to 1,200 sqft as-of-right under state ADU law (Gov Code §65852.2).

Bay Area — permit notes

San Jose runs a strong pre-approved ADU plan program — projects on standard footprints can move to construction inside a quarter.
San Francisco DBI is the longest permit clock in the Bay — plan on 5–8 months for review, with strict planning notification on detached ADUs.
Oakland's hillside zones (Montclair, Piedmont Pines) and EBMUD water-tie-in costs are the biggest cost surprises east of the bridge.
Most Bay cities allow detached ADUs up to 1,200 sqft as-of-right under state ADU law (Gov Code §65852.2).

How we think about adu builder.

An ADU is the single highest-ROI piece of construction most California homeowners will ever do — but only when the building separates cleanly from the main house mechanically, acoustically, and legally. We design every unit as if it will be rented to a stranger on day one: independent panel, independent water shutoff, independent address, independent waste line where the lot allows.

The cheap way to build an ADU is to share systems with the primary residence. It works on paper. It fails in year three when the tenant calls the homeowner about a water heater that lives in the main-house garage. Separation costs 6–9% more up front and recovers it within the first turnover.

We refuse to value-engineer the envelope. The walls, roof, and windows are what the building still has in 30 years; the cabinets and fixtures are not. Spend on R-25 walls, R-49 roof, low-e dual-pane windows, and a properly detailed weather barrier before you spend on stone counters.

The schedule, written out.

Week 0
Feasibility + zoning
Site walk, address-specific zoning pull (LAR1, RM, SF RH-1, etc.), setback + FAR check, easement + utility-locate, soils note. Output: go / no-go memo with realistic budget range.
Week 1–3
Schematic design
Two or three plan options, exterior massing, daylight study, septic / sewer routing, panel-load + HVAC sizing. Output: agreed plan + outline spec.
Week 3–8
Construction documents + Title 24
Stamped architectural, structural calcs, MEP, Title 24 energy report, soils where required. Output: permit-ready set.
Week 8–16
Permit + plan check
City intake, back-and-forth corrections, utility-coordination letters (LADWP, PG&E, EBMUD, SFPUC), school fee + capacity fee assessment, permit issuance.
Week 16–22
Site prep + foundation
Demo, excavation, underground plumbing + electrical, formwork, rebar, pour, foundation inspection.
Week 22–30
Framing + dry-in
Framing, roof sheathing, windows, exterior weather barrier, roofing. Building goes from concrete to lockable shell.
Week 30–38
MEP rough + insulation
Rough electrical, plumbing top-out, ducted heat-pump or mini-split, HERS verification, insulation, drywall.
Week 38–48
Finish + close-out
Cabinets, tile, flooring, paint, fixtures, appliances, exterior hardscape, final inspections, separate-meter release, occupancy.

Materials & assemblies.

Component	Default spec	Why
Wall assembly	2x6 @ 16" o.c. + R-23 batt + ½" ZIP-R + ¾" rainscreen	Continuous insulation closes the thermal bridge that meets Title 24 without crippling the layout.
Roof	R-49 raised-heel truss + radiant barrier sheathing + 30-yr architectural shingle or standing-seam metal	Standing-seam wins on a flat-roof or low-slope detached ADU; shingle is fine on a matched-pitch attached.
Windows	Vinyl or fiberglass, U ≤ 0.30 / SHGC ≤ 0.23, dual-pane low-e	Aluminum frames fail T-24 in almost every CA climate zone.
Heating + cooling	Ducted heat pump (single zone) or ceiling-cassette mini-split	Heat pumps drop ducting complexity and are now cheaper to operate than gas.
Hot water	Heat-pump water heater, 50–65 gal, separate dedicated 240V circuit	Tankless gas is no longer the default — heat pump qualifies for rebates and avoids gas-line trenching.
Subpanel	100A or 125A subfed from main, ground rod at unit, independent disconnect	Independent disconnect is what enables clean future separate-meter conversion.

Hidden costs we flag up front.

Line item	Range	When it hits
Service-panel upgrade	$3K–$12K	main panel is < 200A and you're adding heat pump + EV
Sewer-line replacement	$8K–$28K	pre-1970 clay or cast iron lateral fails camera inspection
Survey + ALTA	$2.5K–$6K	ADU sits within 5 ft of a property line
Tree-protection / removal	$1.5K–$8K	protected tree within drip line of construction
Separate water meter	$5K–$15K	rental and lender requires it
Sprinkler retrofit	$6K–$18K	primary house lacks NFPA 13D and addition triggers it

cheaper alternatives

What we'd consider — and what we wouldn't.

Pre-fab / modular ADU
Lower base price but rarely cheaper all-in once foundation, utility connections, and crane delivery are included; weak on site-specific zoning fit.
Conversion only (no detached)
Faster + cheaper but loses the rental separability and the ROI of a true second dwelling.
Owner-builder
$40K–$80K savings on paper, but most stall in plan-check and lose 6–18 months of carrying cost.

pitfalls — takeover-job patterns

Mistakes to avoid.

Sizing the panel + HVAC for today instead of an electrified future — re-doing it 5 years later costs more than oversizing now
Skipping a sewer-camera before pouring foundation — finding a collapsed lateral after the slab is a $30K+ surprise
Choosing a contractor who has never done a separate-meter coordination — DWP / PG&E paperwork is its own multi-month project
Cheaping out on the weather-resistive barrier — a $400 detail today becomes a $40K mold remediation in year 7

Cost benchmarks from our 2026 California report.

Ranges below are typical installed cost for owner-occupied residential work as of Q1 2026. Drawn from internal job tracking and validated against NAHB cost surveys.

Scope	Los Angeles	Bay Area	Why the spread
Detached new-build ADU	$220–$290	$240–$320	Largest spread — foundation type and access dominate.
Attached ADU / addition	$200–$270	$225–$305	Cheaper per sqft but adds shear-wall + roof tie-in cost.
Garage conversion ADU	$165–$225	$185–$255	Lowest entry if existing slab + walls pass inspection.
JADU (within main house)	$145–$200	$165–$225	≤500 sqft cap; plumbing relocation is the swing item.

Ranges shown $/sqft unless the scope is a flat-fee item (panel, retrofit).

Where the permit actually gets pulled.

City
City of Los Angeles
Plan check
10–18 weeks
Permit + fees
$8.5K–$22K
Standard Plan Program offers preapproved detached ADU sets that cut review to ~4 weeks. JADUs are restricted to within the existing dwelling envelope. No owner-occupancy through 2025.
▸ Hillside Ordinance applies above the BHO line — adds geotech and grading review. Soft-story retrofit required for many pre-1978 multifamily.
Full City of Los Angeles guide →LADBS online services ↗
City
City and County of San Francisco
Plan check
14–28 weeks
Permit + fees
$12K–$38K
ADU + state-density bonus pathway is the fastest route. Mandatory neighborhood notification adds 30 days for many projects.
▸ Mandatory soft-story retrofit applies to wood-frame buildings with 5+ units and ≥3 stories built before 1978.
Full City and County of San Francisco guide →SF DBI Permit Tracking ↗
City
San José
Plan check
10–18 weeks
Permit + fees
$8.5K–$22K
Master ADU Program offers 17 preapproved plan sets — 3-week plan check. Garage conversions exempt from many setbacks.
Full San José guide →San José Accela ↗
City
Oakland
Plan check
12–22 weeks
Permit + fees
$9.5K–$26K
Pre-approved ADU plans available. Wildland-Urban Interface zones in the hills require ember-resistant construction.
▸ Soft-story retrofit program active — confirm parcel status before purchase.
Full Oakland guide →Oakland Accela portal ↗
County
Los Angeles County (unincorporated)
Plan check
8–16 weeks
Permit + fees
$7.5K–$19K
Unincorporated LA County uses a streamlined ADU plan check. School fees collected at final inspection — budget separately.
▸ Fire Hazard Severity Zone overlays apply in foothills — ignition-resistant construction required.
Full Los Angeles County (unincorporated) guide →EPIC-LA self-service portal ↗

When to do it yourself — and when not to.

Situation	DIY-defensible	Call a licensed GC
Garage conversion, slab and roof sound, single bath, no exterior expansion	Owner-builder permit possible if you can run plumbing, electrical, and Title 24 yourself.	Most owners under-scope plumbing and ventilation — a licensed GC finishes faster than DIY discoveries close.
Detached new-build ADU on a flat lot	Not realistic — survey, foundation, shear-wall engineering, and inspections are full-time work.	Always. The Standard Plan pathway only cuts review weeks; field construction still requires a GC.
Hillside or fault-zone parcel	Stop. Geotech is mandatory and grading permits sit outside any DIY pathway.	We run a soils report and structural sheet before signing — non-negotiable.
JADU inside an existing bedroom + bath suite	Tightest DIY-eligible scope: new kitchenette + separate entrance + sub-meter.	Worth a GC if the existing electrical panel needs to grow or any wall is shear-rated.

What this is based on.

1.
California ADU statute (Gov. Code §65852.2) sets minimum standards every city must allow.
California HCD · view source
2.
Standard 60-day ministerial review applies to any complete ADU application.
California HCD ADU Handbook · view source
3.
Owner-occupancy requirements waived statewide through January 1, 2025.
California Legislature — AB 976 · view source
4.
CSLB license required for any contracted ADU work over $500.
Contractors State License Board · view source

ADU Builder — Los Angeles.

ADU Builder — Bay Area.

In short.

How much does an ADU cost in Los Angeles in 2026?: Most detached LA ADUs land between $300K and $500K all-in. Garage conversions typically run $160K–$260K. We hand over a one-page feasibility note with a real number before any contract.
Do you handle LADBS permits?: Yes — full plan set, structural calcs, Title 24 energy compliance, and the LADBS back-and-forth so the homeowner only signs at the milestones.
Can I build an ADU in a hillside zone?: Usually yes, but Hillside Ordinance grading and access rules add design time. We've built in Silver Lake, Mt. Washington, Hollywood Hills, and the Palisades — geotech and shoring are part of the workflow.
How much does an ADU cost in the Bay Area in 2026?: Most detached Bay Area ADUs land between $380K and $620K all-in — roughly 15–25% above LA due to labor, sewer/water tie-in, and hillside access. Garage conversions typically run $190K–$300K.
Which Bay Area city is fastest for ADU permits?: San Jose is the fastest in the Bay — the pre-approved plan program can drop the permit window under 8 weeks for standard lots. Oakland and Fremont are next; SF DBI is the slowest at 5–8 months.

Stay in the same trade

Related adu & housing expansion services.

Same service, other region

ADU Builder across California.

Authority sources

ADU Builder — official California resources.

Primary sources we cross-reference on every project — agencies, utilities, and code bodies whose decisions actually move your permit and budget.

California ADU Handbook
California HCD
Statewide ADU statute, ministerial review rules, and 60-day clock explained.
Terner Center ADU research
UC Berkeley Terner Center
Most current scholarship on California ADU production and economics.
CalHFA ADU resources
California Housing Finance Agency
State financing programs for ADU construction.
CSLB license lookup
California Contractors State License Board
Verify any contractor's license, bond, and complaint history before signing.
California Building Standards Commission
BSC
Authoritative source for the California Building Code (Title 24).

Ready to scope a California adu builder project?

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