What Is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. Think of it as a small, self-contained home with its own kitchen, bathroom, and entrance — built on the same property as your main house.
ADUs go by many names: granny flats, in-law suites, backyard cottages, casitas, or secondary units. Regardless of what you call them, they're one of the smartest investments a California homeowner can make.
Types of ADUs
Detached ADU
A standalone structure in your backyard, separated from your main home. Up to 1,200 square feet under California law. Offers maximum privacy and commands the highest rents.
Attached ADU
Built as an addition to your existing home, sharing at least one wall. Can be up to 50% of your home's floor area. Lower cost than detached since it shares a wall and foundation.
Garage Conversion
Your existing garage is converted into living space. The most affordable ADU option since the structure already exists. California law (SB 13) eliminates parking replacement requirements.
Junior ADU (JADU)
A small unit (up to 500 sq ft) created within your existing home — typically from a spare bedroom. Must have a separate entrance and cooking facility. Can share a bathroom with the main house. Requires owner-occupancy.
Above-Garage ADU
A living unit built on top of a new or existing garage. Great for maximizing limited lot space.
ADU Costs in California
| Type | Cost Range | Timeline |
|------|-----------|----------|
| JADU | Property-specific written estimate | 2-4 months |
| Garage Conversion | Property-specific written estimate | 4-6 months |
| Attached ADU | Property-specific written estimate | 6-10 months |
| Detached ADU | Property-specific written estimate | 8-14 months |
California ADU Laws: What You Need to Know
California has the most progressive ADU laws in the nation. Key provisions:
- No owner-occupancy requirement (AB 976) — except for JADUs
- ADUs can be sold separately as condominiums (AB 1033)
- 60-day permit review mandate for cities
- Ministerial approval — no discretionary review or public hearings
- Reduced setbacks — 4 feet rear and side for detached ADUs
- No parking requirements for garage conversions or near transit
- Fee waivers for ADUs under 750 square feet
- HOAs cannot prohibit ADUs on single-family lots (AB 670)
Benefits of Building an ADU
- Rental Income: $2,000–$3,500/month in LA and OC markets
- Property Value: 20-35% increase with a permitted ADU
- Family Housing: Private space for aging parents or adult children
- Home Office: Dedicated workspace separate from your living area
- Flexibility: Use it for family now, rent it later (or vice versa)
Is an ADU Right for You?
Consider building an ADU if:
- You want to generate rental income to offset your mortgage
- You need housing for aging parents or adult children
- Your property has underutilized space (large yard, unused garage)
- You want to increase your property's value
- You want a dedicated home office or studio
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Vision ADU has completed over 75 ADUs of all types across Southern California. Get a free consultation to see if an ADU is right for your property.
Related Vision ADU Resources
- Garage Conversion vs. New Construction ADU: Which Is Right for You?
- Our Story: How Vision ADU Became Southern California's Most Trusted ADU Builder
- ADU Rental Income: How Much Can You Really Earn in LA & OC?
- ADUs for Multigenerational Living: Keeping Your Family Close
- ADU Contractor in Torrance
- ADU Contractor in Anaheim
- Los Angeles County ADU Builder
- Orange County ADU Builder
- Inland Empire ADU Builder
- 2026 ADU Cost Calculator
- All Vision ADU Service Areas