--- title: "Types of ADUs You Can Build in Los Angeles" description: "Compare every type of ADU in Los Angeles, from detached builds to garage conversions and JADUs, with real costs, sizes." url: "https://adubuilder-losangeles.com/types-adus-los-angeles/" --- # Types of ADUs You Can Build in Los Angeles Los Angeles homeowners have more options for adding living space than most people realize. The types of ADUs Los Angeles property owners can build range from detached backyard cottages to garage conversions to compact junior units carved out of existing floor plans, and a full breakdown of each category is available at [goadu.com](https://goadu.com/). State law, reinforced by local ordinance updates since 2020, now allows most single-family and multifamily lots to add at least one ADU, with many parcels qualifying for two or more. Each type carries its own size limits, setback rules, and construction timelines, so understanding the distinctions before you hire a designer can save months of revision work. ## What an Accessory Dwelling Unit Actually Is An accessory dwelling unit (ADU) is a self-contained residential unit built on the same lot as a primary home. It must include its own kitchen, bathroom, and sleeping space. Los Angeles allows several distinct ADU types, and the right one for your property depends on your lot size, existing structures, budget, and goals. State legislation passed over the past several years stripped away most of the local barriers that once made ADU construction difficult. Today, Los Angeles homeowners have more flexibility than at any prior point, and the Los Angeles Department of Building and Safety (LADBS) processes thousands of ADU permit applications each year. ## Different Types of ADUs in Los Angeles Los Angeles recognizes four main categories: detached ADUs, attached ADUs, garage conversion ADUs, and junior ADUs (JADUs). Each has distinct rules around size, placement, and cost. ### Detached ADU A detached ADU is a fully separate structure built on the same lot as the primary home, with no shared walls. This is the most flexible option in terms of design. You can place it over a new garage, in the backyard, or alongside the primary residence, as long as the structure sits at least 4 feet from the rear and side property lines. The maximum size for a detached ADU in Los Angeles is 1,200 sq ft. Construction costs typically run $300–$500 per sq ft for a site-built unit, putting the full project budget at roughly $150,000–$350,000 after design, permits, and construction are included. These units command the strongest rental income, often $1,800–$3,500 per month depending on the neighborhood and finish level. ### Attached ADU An attached ADU shares at least one wall with the primary dwelling. It functions identically to a detached unit but is structurally connected to the main home. This can reduce foundation costs and sometimes simplifies utility connections. Sizing rules mirror those for detached ADUs: up to 1,200 sq ft, subject to the 4-foot setback requirement on the sides and rear. Attached ADUs work well on narrower lots where there is limited yard depth to place a fully separate structure. Construction costs are similar to detached builds on a per-square-foot basis. ### Garage Conversion ADU A garage conversion ADU converts an existing attached or detached garage into a habitable living space. Because the structure already exists, you are mostly paying for interior work: insulation, drywall, flooring, a kitchenette, a bathroom, electrical upgrades, and mechanical systems. Total project costs for a garage conversion ADU typically range from $80,000–$150,000. That is significantly less than new construction, making it the most common path for homeowners who have an underused garage. One important limitation: a garage conversion reduces or eliminates your covered parking. Los Angeles waives parking replacement requirements for garage conversions in most cases, particularly near transit corridors, but you should confirm this with LADBS for your specific address. ### Junior ADU - JADU A junior ADU (JADU) is carved entirely out of the existing square footage of the primary dwelling. It is capped at 500 sq ft and must include an efficiency kitchen, though it may share a bathroom with the main unit. JADUs are the least expensive option to create, typically costing $40,000–$80,000 because they require no new foundation and minimal structural changes. The trade-off is size and separation. A JADU feels more like a large in-law suite than a truly independent apartment. That said, for homeowners who want to house a family member or generate modest rental income without a major construction project, a JADU is a practical and fast route. ## Can I Build an ADU in My Backyard Los Angeles **Yes, most single-family lots in Los Angeles can accommodate a detached ADU in the backyard.** The primary requirement is maintaining a 4-foot setback from the rear and side property lines. Beyond that, your lot size, existing slope, tree coverage, and utility locations will shape exactly where and how large the unit can be. A site assessment from a licensed architect or ADU contractor will identify any constraints specific to your property. Some hillside lots face additional grading and geological review requirements. Flood zones and fire hazard severity zones also impose conditions that can affect design and cost. ## How Long Does It Take to Get an ADU Permit in Los Angeles Plan check timelines through LADBS vary by submission type. Standard review takes 4–12 weeks. If you use LADBS-approved standard ADU plans, that window shrinks to 1–4 weeks, which is a meaningful time saving on a project that might run 6–12 months from design to certificate of occupancy. Permit fees from LADBS typically run $10,000–$25,000, covering plan check, building permit, and associated city fees. ADUs under 750 sq ft are exempt from local agency impact fees under California state law, which removes one of the larger cost variables for smaller units. ## Which ADU Type Offers the Best Return on Investment Garage conversion ADUs and JADUs offer the fastest payback because their upfront costs are lower. A garage conversion ADU at $80,000–$150,000 generating $1,800–$2,200 per month in rent can return its cost in roughly 5–7 years under favorable conditions. A detached ADU costs more to build but can generate higher rents in desirable neighborhoods, with a typical payback period of 8–15 years across Los Angeles as a whole. The best financial fit depends on what you already have on your property and what your neighborhood's rental market supports. A JADU in a high-demand area near the Westside or Silver Lake will perform better than a larger detached ADU in a lower-demand corridor. ## Prefab and Modular ADUs - Are They Worth Considering Prefabricated and modular ADUs are factory-built units delivered and assembled on site. Total installed costs, including site preparation, foundation, utility connections, and permits, run $200,000–$320,000. That price range overlaps with the lower end of site-built detached ADU construction, so the advantage is not purely cost. The real benefit is speed and design certainty. Prefab manufacturers produce units to fixed specifications, which reduces design iteration and can accelerate the LADBS plan check process if the manufacturer already has pre-approved drawings. Several California-focused prefab companies have units pre-vetted for Los Angeles code compliance, which removes a meaningful layer of uncertainty from the permitting phase. ## Choosing Between ADU Types Start with what your lot already offers. An existing garage points toward a garage conversion ADU. Spare interior square footage in the main house points toward a JADU. A large flat backyard opens the door to a detached or attached ADU. Each type has a clear use case, and the best choice is the one that aligns your available space with your budget and rental or housing goals. Architectural fees for a full custom design run $8,000–$20,000, though pre-approved or prefab plans reduce that figure considerably. Getting a site-specific feasibility review before committing to a type saves time and prevents costly redesigns mid-project. ## Frequently Asked Questions ### Can I Build an ADU in My Backyard in Los Angeles? **Yes.** Most single-family lots in Los Angeles are eligible for a detached ADU in the backyard, provided the structure maintains a minimum 4-foot setback from the rear and side property lines. Hillside lots, flood zones, and fire hazard severity zones may impose additional requirements. A site assessment from a licensed architect will confirm what is feasible on your specific property. ### What Are the Different Types of ADUs in Los Angeles? **Los Angeles recognizes four main ADU types: detached ADUs (separate structures in the backyard or alongside the main home), attached ADUs (connected to the primary dwelling), garage conversion ADUs (existing garages converted to living space), and junior ADUs or JADUs (carved from existing interior space of the primary home and capped at 500 sq ft).** Each type has distinct size limits, setback rules, and cost profiles. ### How Much Does It Cost to Build an ADU in Los Angeles? **Costs vary significantly by type.** A detached ADU typically runs $150,000–$350,000 for a 400–800 sq ft unit including design, permits, and construction. A garage conversion ADU costs $80,000–$150,000. A junior ADU (JADU) generally falls between $40,000–$80,000 because it uses existing interior space. Prefab or modular ADUs land at $200,000–$320,000 fully installed. ### How Long Does ADU Permitting Take in Los Angeles? **Standard plan check review through LADBS takes 4–12 weeks.** Using LADBS-approved standard ADU plans can reduce that to 1–4 weeks. Permit fees typically range from $10,000–$25,000. ADUs under 750 sq ft are exempt from local agency impact fees under California state law, which reduces overall costs for smaller units. ### What Is the Maximum Size for an ADU in Los Angeles? **A detached or attached ADU in Los Angeles can be up to 1,200 sq ft, in line with California state law.** A junior ADU (JADU) is capped at 500 sq ft because it must be created entirely within the existing footprint of the primary dwelling. These limits apply as of current Los Angeles code, so confirming with LADBS before finalizing your design is advisable.