Detached ADU Construction in Los Angeles
A detached ADU is a standalone structure on the same property as your main home, giving you a private, independent living space with its own entrance, kitchen, bathroom, and utilities. Renova Built designs and constructs custom detached accessory dwelling units in-house, from architectural plans and permits to final inspection, on one fixed-price contract.
What Is a Detached ADU?
Why Homeowners Choose Renova Built for Detached ADUs
- Custom new construction, not prefab, so your detached ADU is designed around your lot and finished to match your existing home
- Single-story and two-story detached ADUs, including two-story builds that are common on smaller Los Angeles lots where building up preserves usable yard space
- Complete in-house service, from architectural design and 3D renderings to permits, Title 24 compliance, and final inspection
- Fixed-price contracts with a no change orders approach, so your budget stays locked from day one
- Free consultations with a property evaluation and feasibility assessment before you commit
Detached ADU Sizes We Build (400 to 1,200 sq ft)
Under California law, a detached ADU can reach up to 1,200 sq ft, the largest footprint of any ADU type. We build across the full range, and the right size depends on your goals, your budget, and how much available land your lot allows after setbacks and lot coverage.
Best for: rental income or a home office. Open-concept or one-bedroom living with a full kitchen and bathroom in a compact footprint that fits lots with limited space.
Best for: small families or stronger rental income. A true two-bedroom layout that still pencils out, our most requested size for long-term tenants.
Best for: larger families or maximum rental income. The largest footprint California allows, with room for a laundry area and up to two baths.
Which Detached ADU Layout Fits Your Goals
The bedroom configuration you choose shapes both your upfront cost and your long-term return. Here is how the three most common detached ADU layouts line up with what homeowners want from the space.
One-Bedroom / Studio Layout
Best when your priority is a fast payback or a home office. A studio or one-bedroom keeps construction cost down and fits lots with limited available land, while still delivering a fully independent living space with its own entrance.Two-Bedroom Layout
Best for small families, adult children, or steady rental housing. Two bedrooms, a full kitchen, and a dedicated living space make the unit feel like a real home while staying cost-effective enough to pencil out.Three-Bedroom Layout
Best for larger families or maximum rental income potential. At up to 1,200 sq ft with a laundry area and one to two bathrooms, a three-bedroom detached ADU commands the highest rents and adds the most property value in desirable neighborhoods.Not sure which detached accessory dwelling unit layout is right for your lot? We walk through the trade-offs during your free site assessment, weighing your goals against setbacks, lot coverage, and available space so you invest in the configuration that serves you best.
Detached ADU Cost by Size
Detached ADU cost varies by size, finish level, site conditions, and utility connections. These are typical ranges for custom new construction in our service area, not a fixed quote.
| Detached ADU size | Typical range |
|---|---|
| Studio / one-bedroom, 400 to 600 sq ft | $150K to $250K |
| Two-bedroom, 600 to 900 sq ft | $210K to $360K |
| Three-bedroom, 900 to 1,200 sq ft | $340K and up |
Your final pricing depends on site conditions, the finishes you choose, and permit fees. Cost drivers include sloped or hillside lots that need extra foundation work, long utility trenching runs to a standalone structure, poor soil that requires special foundations, and finish level, since high-end materials raise cost per square foot. Soft costs like design, engineering, and Title 24 compliance are included in our fixed-price estimate, so there are no hidden fees. For a full breakdown by ADU type, see our ADU cost guide, and to fund the build, our ADU financing overview walks through the options.
Detached ADU Project Examples Across Our Service Area
Detached ADU cost and rental potential vary across our counties. These are typical examples based on size, region, and finish level, not guaranteed outcomes.
| Configuration | Size | Region | Typical cost | Typical monthly rent |
|---|---|---|---|---|
| Studio detached, standard finishes | ~500 sq ft | San Bernardino County | $180K to $230K | $1,700 to $2,000 |
| One-bedroom detached, mid finishes | ~750 sq ft | Los Angeles County | $250K to $300K | $2,300 to $2,800 |
| Two-bedroom detached, premium finishes | ~1,000 to 1,200 sq ft | Orange County | $350K and up | $3,500 to $4,500 |
San Bernardino County typically offers the most cost-effective entry point for detached ADU construction, while coastal Orange County and premium Los Angeles neighborhoods run higher per square foot. Rental figures are typical ranges that depend on neighborhood, finish level, and square footage. Building permit fees generally run a few thousand dollars depending on unit size and jurisdiction, and a permitted detached ADU can add meaningful property value, though every property and market is different.
Our Detached ADU Construction Process
Our process takes your detached ADU project from the first consultation through certificate of occupancy, with one point of contact throughout.
Free Site Assessment and Design Consultation
We evaluate your property for required setbacks, utility routing distances, soil and slope conditions, lot coverage, and overall feasibility for a detached ADU. Then our in-house architects create custom architectural designs and 3D plans specific to your lot, with no generic templates, so you see exactly what your standalone unit looks like before you commit.Permitting and Approvals
We prepare and submit your complete building permit application, including structural plans, Title 24 energy compliance documentation, and supporting engineering. We handle plan-check corrections, city reviewer questions, and revisions, and we manage Title 24 in-house so you do not coordinate separately with energy consultants. For the full picture of California ADU law and fees, see our ADU cost guide.Construction
Construction begins with foundation work, then framing, mechanical, electrical, and plumbing rough-in, and interior and exterior finishes. We build both single-story and two-story detached ADUs. A two-story build is a common choice on smaller Los Angeles lots where building up preserves usable yard space, and we handle the added structural engineering in-house so your budget and schedule stay predictable.Final Inspection and Move-In
After construction, we coordinate final city inspections and secure your certificate of occupancy, the document that legally allows the unit to be occupied and rented. We walk you through the finished, permitted detached ADU before we hand over the keys, whether you are welcoming family or your first tenant.
In-House Architects, One Team, One Contract
Why We Build Custom, Not Prefab
Start Your Detached ADU Project Today
You have the available land, and Southern California’s ADU regulations make it easier than ever to build. Tell us about your property and we will reach out, usually within one business day, to walk you through your detached ADU options and a transparent, fixed-price estimate. No pressure, no obligation. Call (818) 968-2981 or send your details.
Detached ADU Questions, Answered
What is a detached ADU?
A detached ADU is a standalone structure on the same property as your main home, built as its own separate building with its own foundation, roof, utilities, kitchen, bathroom, and entrance. It provides an independent living experience with maximum privacy and flexibility. Detached ADUs must comply with local zoning laws, and permits are required for all new detached ADUs to ensure legality.How much does a detached ADU cost in Southern California?
Custom detached ADU construction typically runs $150K to $360K and up depending on size, finishes, and location. A studio or one-bedroom around 400 to 600 sq ft runs $150K to $250K, a two-bedroom from 600 to 900 sq ft runs $210K to $360K, and a three-bedroom from 900 to 1,200 sq ft runs $340K and up. Coastal Orange County and premium Los Angeles neighborhoods push higher. Final pricing depends on site conditions, finishes, and permit fees, and these figures include design, permits, Title 24 compliance, site work, and construction.How long does detached ADU construction take?
Construction typically runs 4 to 6 months, with the full process from consultation through certificate of occupancy running about 8 to 13 months under favorable conditions. Permitting and plan check take roughly 2 to 3 months, and California law requires cities to respond to a complete application within 60 days. Projects with a two-story build, hillside lots, historic overlays, fire hazard zones, or complex site conditions can extend to 10 to 18 months total.How big can a detached ADU be in California?
Under California law, a detached ADU can reach up to 1,200 sq ft, the largest footprint of any ADU type. We build across the full 400 to 1,200 sq ft range. The right size for your lot depends on setbacks, lot coverage, and how much available land you have, and we confirm what your property allows during the free site assessment.Can you build a two-story detached ADU?
Yes. Renova Built builds both single-story and two-story detached ADUs. A two-story detached ADU is a common choice in Los Angeles, especially on smaller lots where building up preserves usable yard space and still delivers a full-size unit. A two-story build adds structural engineering and some cost compared with a single-story unit, and we handle that engineering in-house and walk you through the trade-offs at your free consultation.What is the difference between custom and prefab detached ADUs?
Custom detached ADUs are entirely new construction built on-site from the ground up, with the foundation, framing, roofing, and all systems designed specifically for your lot, giving you full control over layout, materials, and finishes to match your main residence. Prefab or modular units are manufactured off-site and transported in, which can reduce build time but limits design flexibility, finish options, and exterior appearance, and adds transport and crane costs. Renova builds custom, not prefab.Does a detached garage count as an ADU?
Not on its own. A detached garage becomes an ADU only after it is legally converted with independent living, sleeping, and sanitation facilities, meaning its own kitchen, bathroom, and separate entrance, and passes final inspection. Converting an existing detached garage is often a lower-cost path than new construction, and we cover it on our garage conversion page. A new detached ADU is often preferable because you can keep your existing garage while building a standalone unit elsewhere on the lot.Do I need to provide parking for a detached ADU?
In most cases across Los Angeles, Orange County, and San Bernardino, no additional parking space is required if your property is within half a mile of a major transit stop, and California law typically does not require replacement parking even if you demolish or convert an existing garage. Outside transit zones you may need one parking space per unit, though local rules vary. We evaluate parking compliance during the design phase so there are no surprises during the permitting process.Keep Planning Your ADU
A detached ADU is one of several ways to add space on the property you already own. Compare your options and understand the numbers before you break ground.