Everything homeowners need to know about building an accessory dwelling unit in Lancaster - size limits, setbacks, permits, and how the city's own standards layer on top of California's statewide by-right ADU law.
Last verified: August 2026
8/10 · Very ADU-friendly
850-1,000 sq ft*
Max ADU size
18 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Lancaster Municipal Code Chapter 17.41 (Accessory Dwelling Units and Junior Accessory Dwelling Units) and California's statewide ADU law (Government Code, State ADU Law, Sections 66310-66342) for general reference - it is not legal advice. Regulations change; always confirm current requirements with Lancaster Community Development before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
850 sq ft for a studio or 1-bedroom unit; 1,000 sq ft for a 2-bedroom (or larger) unit
18 ft (up to 20 ft with a roof pitch matching the primary dwelling)
Sized by bedroom count under LMC 17.41.016, not a flat square-footage cap
Same 850 / 1,000 sq ft caps by bedroom count, or 50% of the primary dwelling's floor area, whichever is smaller
Matches the primary structure
Common approach for above-garage conversions
Junior ADU (JADU)
500 sq ft
Same as primary structure
Must be built within the existing walls of the primary home
Allowed zoning districts
Citywide on lots zoned for single-family or multi-family residential use (R-7,000, R-10,000, MDR, HDR and similar districts) under LMC Chapter 17.41. The underlying zone still sets a lot-coverage cap for the property as a whole (for example, 50% in the R-7,000, MDR, and HDR districts). Confirm your parcel's zone and coverage limit with Lancaster Community Development before you design.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft from side and rear property lines for new detached construction; 25 ft front setback; conversions of legally established structures (like an existing garage) are exempt from these setbacks
Parking
1 space per ADU unless the project qualifies for a state-law exemption (within a half-mile of public transit, a conversion of existing space, or another listed exemption); no replacement required for a demolished garage space
Units per lot
1 ADU + 1 JADU on a single-family lot. Multifamily lots follow state law, including up to 8 new detached ADUs under SB 1211
Owner-occupancy
Not required for ADUs, permanently eliminated statewide by AB 976 effective January 1, 2024. A JADU requires an on-site owner only if it shares sanitation facilities with the primary home
Building code
Must meet the California Residential Code as locally adopted by Lancaster (2025 California Building Standards Code cycle, effective January 1, 2026)
Rental rules
No separate ADU-specific rental license was found in the municipal code; standard California landlord-tenant law applies
Ordinance history
How Lancaster's ADU rules got here
2017Statewide by-right ADU law takes effect. California's original ADU statute begins requiring cities, including Lancaster, to approve most ADUs ministerially rather than through discretionary review.
2020State law overhaul reshapes local codes. AB 68, AB 881, and SB 13 take effect January 1, mandating 60-day ministerial review, capping setbacks at 4 ft, and barring minimum-lot-size rules - the framework Lancaster's current LMC Chapter 17.41 development standards are built on.
2024Owner-occupancy ban made permanent. AB 976, effective January 1, permanently prohibits California cities from requiring owner-occupancy for ADUs.
2026New building code, state recognition. Lancaster adopts the 2025 California Building Code cycle for new submittals effective January 1. On January 6, HCD awards the city its Prohousing Designation for housing-production policies that include its ADU program, and on August 20, HCD names Lancaster among 13 California communities sharing $11.3 million in Prohousing Incentive Pilot funding.
Worth knowing: HCD's public ADU ordinance enforcement-letters dashboard lists no findings or violation letters for Lancaster as of mid-2026 - a contrast with some neighboring Antelope Valley cities, where the state has flagged outdated local ordinances. Lancaster also runs a pre-approved ADU plan program (five architect-designed floor plans from 370 to 1,200 sq ft) and an ADU Assistance Loan Program offering a deferred-payment, no-interest loan of up to $10,000 toward soft costs for income-qualified owner-occupants who agree to rent the ADU to a lower-income household.
Permit process
How Lancaster ADU permitting works
1
Pre-application check
Confirm your zone and lot-coverage cap with Lancaster Community Development before you design. Reach Planning at planning@cityoflancasterca.gov.
2
Choose a plan path
Pick one of the city's five pre-approved ADU floor plans (370-1,200 sq ft) for faster review, or submit a fully custom design.
3
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, plus existing floor plans of the primary home if you're relying on the 50%-of-primary-dwelling size option.
4
Submit your application
File through the Citizen Access Portal (Accela) or in person. Because ADUs are approved by right, applications go directly to Building & Safety rather than a separate discretionary Planning review.
5
Plan review
State law requires a decision within 60 days of a complete application.
6
Permit, build, inspect
Pull your building permit, begin construction, and schedule framing, plumbing, electrical, and final inspections.
Estimated permit fees run roughly $3,500-$12,000 and are reported to be among the lowest in Los Angeles County. Fees and timelines are approximate - confirm current figures with Building & Safety at (661) 723-6144 or permits@cityoflancasterca.gov.
Budgeting
What it costs to build an ADU in Lancaster
Garage conversion
Roughly $60,000-$170,000, the least expensive path since the shell already exists
Basement conversion
Uncommon in Lancaster's largely slab-on-grade, high-desert housing stock; where feasible, costs typically run comparable to or higher than a garage conversion
New detached ADU
Roughly $130,000-$310,000+ for a code-compliant, fully insulated freestanding unit
Permit fees
Reported at roughly $3,500-$12,000, among the lower fee schedules in LA County
Impact fees
Waived entirely for ADUs under 750 sq ft under state law
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and whether utilities need to be extended. Antelope Valley's summer heat and winter cold both push insulation and HVAC costs above what a garage shell alone would suggest.
Before you apply
Tips for a smooth approval
Confirm your zone and lot-coverage cap before you design. The ADU size caps are citywide, but the underlying zone's overall lot-coverage limit still applies to your property as a whole.
Size by bedroom count, not just square footage. Lancaster caps a detached ADU at 850 sq ft for a studio or 1-bedroom and 1,000 sq ft for 2+ bedrooms, so your floor plan's bedroom count sets your ceiling.
Look at the pre-approved plans first. Five architect-designed floor plans from 370 to 1,200 sq ft can meaningfully cut plan-check time compared to a fully custom design.
Ask about the ADU Assistance Loan Program. Income-qualified owner-occupants who agree to rent the ADU to a lower-income household may qualify for deferred, no-interest financing toward soft costs.
Keep an eye on the 750 sq ft impact-fee threshold. Staying under that line waives development impact fees entirely under state law, which can meaningfully change your project's math.
FAQ
Common questions
Do I need to live on the property to build an ADU in Lancaster?
No. California's AB 976 permanently eliminated owner-occupancy requirements for ADUs statewide as of January 1, 2024, so you can build and rent out an ADU without living on site. A JADU requires an on-site owner only if it shares sanitation facilities with the primary home.
How many ADUs can I build on one lot?
On a single-family lot, 1 ADU plus 1 JADU in addition to the primary dwelling. Multifamily properties follow state law, which allows up to 8 detached ADUs on qualifying lots.
Do I need extra parking for an ADU?
Usually one space, unless your project qualifies for an exemption, such as being within a half-mile of transit or converting existing space like a garage. A demolished garage space doesn't need to be replaced.
How long does the permit process take?
State law requires a decision within 60 days of a complete application. Because ADUs don't require separate Planning approval, applications move directly to Building & Safety review. Confirm current timelines at (661) 723-6144.
What's the maximum size for a detached ADU in Lancaster?
850 sq ft for a studio or 1-bedroom unit, or 1,000 sq ft for a 2-bedroom or larger unit, with a height limit of 18 ft (up to 20 ft with a matching roof pitch).
How much does an ADU cost to build in Lancaster?
Garage conversions tend to run roughly $60,000-$170,000, and new detached units roughly $130,000-$310,000 or more, based on local contractor estimates and regional reporting. Permit fees are reported at roughly $3,500-$12,000, among the lower fee schedules in LA County, and units under 750 sq ft are exempt from impact fees entirely.
Has the state flagged any compliance issues with Lancaster's ADU ordinance?
Not as of mid-2026. HCD's public ADU ordinance enforcement-letters dashboard lists no findings or violation letters for Lancaster, unlike some neighboring Antelope Valley cities where outdated local ordinances have been flagged. Confirm current status with Community Development, since ordinances and state review continue to evolve.
Does Lancaster offer pre-approved plans or financial help for building an ADU?
Yes. The city offers five pre-approved ADU floor plans (370-1,200 sq ft) to speed up permitting, and an ADU Assistance Loan Program that provides deferred-payment, no-interest financing of up to $10,000 for income-qualified owner-occupants who rent the ADU to a lower-income household.
