Los Angeles ADU garage conversion costs, permits and 2026 fast track rules

Why LA homeowners are rushing to convert garages into ADUs

Across Los Angeles proper, the San Fernando Valley, and Eastside neighborhoods, homeowners are staring at the same math:

• Mortgage locked at a low rate

• Home values are high

• Rental demand has not cooled

At the same time, the region is still rebuilding from wildfires, and the very first completed rebuild in Altadena was a 630 square foot ADU that replaced a garage.Politico

With new ADU bills and a county-level ordinance that kicked in August 28, 2025, LA homeowners now have:

• Clearer rules on setbacks and height

• Pre-approved ADU plan programs rolling out under AB 1332

• Faster permit timelines if you choose the right path

Garage conversions are the fastest way to turn an underused structure into real housing or income.

What does a 2026 ADU garage conversion really cost in LA?

With California construction and LA labor pricing where it is today, expect:

ADU garage conversion (existing detached garage)

For a typical 400–600 square foot garage in LA:

• Basic code compliant conversion Approx. $190k–$230kNew slab work where needed, full insulation, new electrical, plumbing, windows, doors, interior finishes and tie in to existing utilities.

• Higher finish conversion with upgrades Approx. $220k–$260k+Better cabinetry, tile, glazing, roof upgrades and landscape improvements around the unit.

New detached ADU in the backyard

For a new 500–800 square foot ADU:

• Approx. $230k–$350k+, depending on design complexity, site work, retaining walls and level of finish.

These ranges assume:

• A licensed GC like California Construction & Remodeling Experts handling the entire build

• Owner working with pre-approved or efficient plan sets

• No extraordinary hillside, soils or access issues

  

Technical: ADU laws, LA County rules and fast track permitting

1. LA County ADU Ordinance (effective August 28, 2025)

The LA County ADU Ordinance Amendment took effect August 28, 2025, updating local standards to align with California’s statewide ADU rules.LA County Planning+2LA County Planning+2

Highlights relevant to garage conversions:

• Clarified setbacks, height limits and lot coverage for both detached and conversion ADUs

• Streamlined ministerial approvals (no public hearing) when you meet the standards

• Greater consistency across unincorporated LA County and city jurisdictions for basic ADU criteria

If your property is within unincorporated LA County, these standards define what is allowed and make it easier to get clear answers early.

2. Pre-approved plans under AB 1332

Assembly Bill 1332 requires local agencies to create a pre-approved ADU plan program by January 1, 2025.City of Lincoln+3Digital Democracy | CalMatters+3LegiScan+3

In practice, that means:

• Cities and counties must accept standard ADU plans that meet building codes and then apply them repeatedly to new sites

• Owners can select from a catalog of pre-approved plans, paying a plan fee once and reducing design weeks

• Many jurisdictions, including LA-area cities and counties, are moving toward 30–60 day approvals for ADUs that use these plansJustin Borges+2ahcd.assembly.ca.gov+2

  
  

For a garage conversion, you might:

• Use a pre-approved interior layout and envelope details

• Combine it with site specific drawings for grading, utilities and driveway changes

3. Wider ADU law updates

Recent ADU legislation continues to:

• Reduce or eliminate owner occupancy requirements

• Make it easier to legalize existing unpermitted ADUs

• Clarify parking and design restrictions so more lots qualifyahcd.assembly.ca.gov+2ADU West Coast+2

  
  

For LA homeowners, this means an older garage or bonus room may be closer to legal conversion than you think, provided the structure can meet current codes safely.

How-To: Step-by-step plan for a 2026 Los Angeles ADU garage conversion

Step 1: Confirm zoning and ADU eligibility

Before spending money:

1. Identify whether you are in city of Los Angeles, another city, or unincorporated LA County.

2. Check the local ADU eligibility and zoning map or talk to your planner or GC.

3. Confirm basic constraints:

   • Lot zoning

   • Existing structures

   • Fire zone or hillside overlays

This is where a local ADU builder like California Construction & Remodeling Experts can quickly confirm feasibility.

Step 2: Assess your existing garage

A site visit should answer:

• Is the slab sound or will it need partial or full replacement?

• Are walls straight, dry and structurally sound?

• How close is the garage to property lines and the main house?

• Will you need to raise the roof for head height?

Sometimes it is actually cheaper to demolish and rebuild as a new ADU rather than force an unsafe or badly built garage into compliance.

Step 3: Pick the right design path

You typically have three routes:

1. Pre-approved plan (fastest permitting)

   • Choose a plan from an approved catalog that fits your size and layout needs

   • Add site specific details and submit under the local AB 1332 pre-approved programDigital Democracy | CalMatters+2Solano County+2

2. Modified pre-approved plan

   • Start with a pre-approved base

   • Make limited changes that still keep most details intact

   • Permitting may take slightly longer but stays faster than fully custom

3. Custom design

   • Best for awkward sites, hillsides, or high end projects that need a specific layout

   • Expect more design time and permit review, but you gain flexibility

     

Step 4: Map your ADU permit timeline

If you use a pre-approved or standard plan and your site is straightforward, your target should be:

• Design and site documentation: 4–8 weeks

• Permit review (ministerial): ideally 30–60 days for fully compliant submittalsJustin Borges+2ahcd.assembly.ca.gov+2

  
  

For more complex sites or fully custom designs, expect a longer review and potential comments from plan check.

Step 5: Budget and finance reality check

Once you have a concept:

1. Align the scope to the cost ranges above

2. Include:

   • Soft costs (design, engineering, surveys, permits): usually 15–20 percent

   • Contingency at 10–15 percent

3. Explore financing such as HELOC, cash out refinance or construction financing if needed

Remember that in many LA neighborhoods, a well designed ADU can produce $2,000–$4,000+ monthly rent, depending on size and location.Justin Borges+1

Step 6: Construction and inspections

A typical ADU garage conversion build phase lasts:

• 4–6 months for straightforward conversions

• Longer for full rebuilds, tricky access or utility upgrades

Your GC should:

• Coordinate inspections with LADBS or your local building department

• Manage trenching for new sewer and electrical as needed

• Keep neighbors informed about schedule and noise

Step 7: Close-out and long term use

Once the unit passes all final inspections:

• Secure your certificate of occupancy

• Decide whether you will rent long term, use as family housing or hybrid

• Keep a complete record of plans, permits and inspection sign-offs for refinancing, resale or future upgrades

FAQ – Los Angeles ADU garage conversions in 2026

1. Is a garage conversion cheaper than building a new detached ADU?

Usually yes. Converting a sound existing garage is typically less expensive than building a new ADU from the ground up, but if the structure is in poor condition, a new build can be the smarter long term move.

2. How long does it take to get an ADU garage conversion permit in LA now?

With a pre-approved or standard plan and a clean site, many jurisdictions aim for 30–60 day approvals under AB 1332 and current ADU reforms. More complex sites or custom designs can take longer. Digital Democracy | CalMatters+2ahcd.assembly.ca.gov+2

3. Are ADUs in Los Angeles subject to rent control?

New ADUs are often exempt from LA’s rent stabilization ordinance for a set period but remain subject to state rent cap rules. Exact treatment varies by location and building status, so owners should confirm with local housing guidelines. Justin Borges+1

4. Can I convert my garage to an ADU if I already have a guest unit?

In many cases, yes. Recent ADU laws even allow multiple ADUs on some lots, especially multifamily properties. The exact number and type depend on local zoning and state caps, so a quick feasibility check with an ADU-experienced GC or planner is key. ahcd.assembly.ca.gov+1

Author Bio, CTA and Links

California Construction & Remodeling Experts is a licensed Los Angeles contractor serving LA proper, the San Fernando Valley and Orange County, specializing in ADUs, garage conversions, kitchens, baths and full home remodels.

Ready to convert your LA garage into a legal ADU in 2026? Schedule a free ADU consult with California Construction & Remodeling Experts at calbuildremodel.com

.We will review your site, ballpark costs and map the fastest permit path for your property.

Internal links

• California Construction & Remodeling Experts – ADU and Garage Conversion Services

  
  

External authority links

• LA County ADU Ordinance Amendment – Official Planning Page LA County Planning+1

• California ADU Handbook – State HCD ahcd.assembly.ca.gov