Arcadia’s tree-lined neighborhoods and generally larger backyards create real room for detached cottages, garage conversions, or tasteful additions. The City has invested in homeowner-friendly ADU resources, including step-by-step checklists and a Pre‑Approved Detached ADU Program that can save fees and shorten review time. State housing law also requires ministerial, objective review for qualifying ADUs, so red tape is lower when plans are complete and code aligned.
An Accessory Dwelling Unit is a self-contained residential unit with its own kitchen, bath, and sleeping space on the same lot as a primary home. Arcadia recognizes attached ADUs, detached ADUs, and conversion ADUs created from existing enclosed spaces such as a garage, pool house, or other accessory structure. Junior ADUs, up to 500 square feet and carved from within the main home, are also allowed when specific criteria are met.
Own a single-family lot with an existing or concurrently built primary dwelling? Arcadia lets you choose one path:
One attached ADU; or
One detached ADU or one JADU; or
One detached ADU plus one JADU together.
Conversion of ADUs from existing permitted enclosed spaces is also allowed, and you enjoy relaxed setbacks when you keep the footprint. citeturn1view1turn1view2
Detached or attached units over 800 square feet trigger a Zoning Clearance. Adding an ADU cannot push the total floor area ratio above 45 percent, lot coverage above 50 percent, or reduce the required open space below 50 percent. Maintain at least 6 feet of building separation eave to eave between a detached ADU and the main house. These are objective measures that the City will verify during review.
State law limits side and rear setbacks for new attached or detached ADUs to 4 feet. No new setback is required when you convert an existing permitted living area or accessory structure in place, unless needed for fire safety. Arcadia guidance mirrors these rules.
If you own apartments or a mixed use property, Arcadia gives you two choices, pick one: create interior ADUs in unused spaces such as storage rooms up to 25 percent of the existing unit count, or build up to two detached ADUs, each limited to 800 square feet, one story, and 16 feet in height, with 4 foot side and rear setbacks.
Parking rules no longer block backyard projects. California limits parking to one spot per ADU or bedroom, whichever is less, allows tandem parking on existing driveways, and prevents cities from requiring parking replacement when garages are converted or demolished for ADUs. Many ADUs qualify for zero parking, especially if near transit, inside the existing home, in historic districts, or near car share vehicles.
California law forbids local agencies from requiring owners to live on-site for ADUs. You can rent out both your main home and ADU long-term. Junior ADUs have different rules, so check before you start.
ADU permits are ministerial, with agencies required to approve or deny within 60 days of a complete application. They have 30 days to request corrections, and if they miss deadlines, your permit is deemed approved. Getting plans right upfront protects your timeline.
Arcadia offers a Pre-Approved ADU Program where professionals submit detached ADU designs for city pre-review. Homeowners choosing these plans skip Planning review, save about $700 in fees, and get faster building plan checks. These approvals stay valid until code updates.
Custom ADUs usually cost $100,000 to $350,000+, while prefab options range from $90,000 to $180,000 before upgrades. Costs break down roughly into design (8-12%), permits (5-10%), site prep (5-15%), utilities (5-10%), construction (45-60%), finishes (10-15%), and contingency (10-15%). Units under 750 sq ft may qualify for fee waivers, so right-sizing can save you money.
Match your ADU’s roof and exterior materials to your home for a seamless look. Use sliding or pocket doors to save space. Place windows for privacy and garden views, not into neighbors’ homes. A small porch facing the yard improves livability and rental appeal. Durable, mid-grade finishes photograph well if you plan to rent. Standardized sizes that fit typical Arcadia yards speed permits through pre-approval.
Options include home equity loans, cash-out refinancing, construction-to-perm loans, and some state or local grants. California programs like CalHFA and SB13 impact fee waivers for small units help lower entry costs. Be sure to check current availability when budgeting.
Here is how we approach ADU construction Arcadia projects so you can move forward with confidence.
Site & Code Review
We verify zoning, lot lines, utilities, and constraints, then outline feasible ADU footprints under Arcadia and state rules.
Concept & Budget Alignment
We sketch space plans, run preliminary cost models, and align the scope with your budget and use goals.
Full Plans Or Pre-Approved
Choose a custom design or leverage a City pre-approved plan to save money and time.
Permit Management
We prep submittals, respond to comments, and track the 30 and 60 day clocks so nothing slips.
Build With Transparency
Our field team coordinates trades, inspections, and weekly progress updates, with clear change order control.
Closeout & Turnover
Final inspections, punch, warranty handoff, and optional rental prep if you plan to lease the unit.
Ready for your project? Reach out and let us walk your property.
How big can I build? Arcadia must allow at least an 800 square foot ADU that meets 4-foot side and rear setbacks, and cities cannot use lot coverage or FAR rules to block that minimum. Larger units are possible within FAR, lot coverage, and height limits; detached multi-family ADUs top out at 800 square feet and 16 feet high per unit. citeturn5view0turn1view6
Can I convert my existing garage? Yes. Conversion of ADUs is allowed, and you do not have to replace the removed parking. No new setback is required if you stay within the permitted footprint unless fire safety requires it. citeturn5view0turn1view1
Can I rent the ADU short term? Cities may require rental terms longer than 30 days, and many do. Check the current Arcadia policy before you list. citeturn5view0
Do I have to live on site? No owner occupancy requirement applies to ADUs; investors can rent both units. Junior ADUs differ. citeturn6search0turn6search6
How long does permitting take? After a complete submittal, the City must act within 60 days. Incomplete plans reset the clock.
If you are reading this, you are serious. Tell us about your property, your goals, and your timing. We will review zoning, run a quick feasibility scan, and schedule an on-site walk. From there, we produce a clear scope, line-item budget, and target start date for your ADU construction Arcadia project. Use the form, call, or chat, and we will get rolling.
Prefer to talk to a real person? Call us or send photos of your yard and existing structures. We respond fast. Your path to flexible, income producing, multi-generational living starts with one conversation about ADU construction in Arcadia.
| Zip Code | Area Code | City | County | State |
| 91006 | 323 |626 |714 |818 | Arcadia | Los Angeles | CA |
| 91007 | 310 |626 |818 | Arcadia | Los Angeles | CA |
| 91066 | 626 | Arcadia | Los Angeles | CA |
| 91077 | 626 | Arcadia | Los Angeles | CA |
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