ADU Types
Which type of ADU is right for your property?
There are four main ADU types in Sacramento: detached ADUs (free-standing backyard homes), attached ADUs (additions with their own entry), garage conversions (an existing garage turned into a home) and junior ADUs (up to 500 sq ft inside your house). The right one depends on your lot, budget and how you will use it.
Side by side
How do the four ADU types compare?
The short answer: garage conversions and junior ADUs cost the least and finish fastest, detached ADUs offer the most space and privacy, and attached ADUs sit in between. Here is the full comparison.
| ADU type | Typical size | Typical timeline | Typical cost (estimate) | Best for |
|---|---|---|---|---|
| Detached ADUs | Commonly up to 1,200 sq ft | About 9 to 14 months | $150,000 to $300,000+ | Rental income, aging parents, maximum privacy |
| Attached ADUs | Up to 50% of the main home, size limits apply | About 8 to 13 months | $100,000 to $300,000 | Smaller yards, multigenerational living |
| Garage Conversions | Existing garage footprint, often 400 to 600 sq ft | About 6 to 10 months | $80,000 to $150,000 | Lower budgets, faster timelines |
| Junior ADUs | Up to 500 sq ft | About 4 to 8 months | $50,000 to $100,000 | Lowest cost, caregivers, young adults |
Rules vary by jurisdiction and change often. Call us to confirm what applies to your property.
What is an ADU?
An ADU, or accessory dwelling unit, is a second, complete home on a single-family lot. It has its own kitchen, bathroom and entrance, and it can be rented, used for family, or used as a home office or studio. California law requires cities and counties to allow ADUs on most residential lots, and Sacramento has been one of the more welcoming jurisdictions in the state.
How do I choose between ADU types?
Start with three questions. What is already on your lot? What will the unit be used for in the next ten years? And what is a comfortable budget? A sound detached garage points toward a conversion. A deep backyard with room for privacy points toward a detached ADU. A small yard or a parent who needs to be close often points toward an attached ADU or a junior ADU.
You can also combine types. One ADU plus one junior ADU is generally allowed on a single-family lot, so a detached cottage in the yard and a junior suite inside the house can coexist.
Which ADU type earns the most rent?
Detached ADUs usually earn the highest rent because they offer full privacy and feel like a small house. Garage conversions often come close for less money, especially on alley lots in older Sacramento neighborhoods. Junior ADUs rent for less but cost far less to create.
Which ADU type is fastest?
Junior ADUs are usually fastest, about 4 to 8 months from first visit to move-in. Garage conversions follow at about 6 to 10 months. Attached and detached units take longer because they involve new foundations and more complex permits.
Not sure? Request a quote and we will walk your lot and tell you plainly which options make sense. You can also read our guide on garage conversion vs detached ADU.
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