ADUs for Multi-Family Properties: What You Need to Know
Many homeowners know that California allows ADUs on single-family lots, but fewer realize that multi-family properties can qualify too. The rules are different, and understanding them can open valuable opportunities for property owners.
1. Who Can Build an ADU on Multi-Family Property?
Only the property owner or authorized representative (not tenants) can apply. The property must already contain at least one legal dwelling unit.
2. What Types of ADUs Are Allowed
Conversion ADUs: Existing non-living areas—such as storage rooms, garages, boiler rooms, or basements—can be turned into new units. You can create up to 25% of your existing unit count this way.
Detached ADUs: You may also build up to two new detached ADUs anywhere allowed on the lot, meeting setbacks and fire-access standards.
3. Typical Size and Zoning Limits
Detached ADUs can reach up to 1,200 square feet, depending on local zoning. Converted ADUs depend on the size of existing spaces. Local cities may add height or parking requirements.
4. Why Multi-Family ADUs Matter
For landlords and property investors, adding ADUs can increase rental income and overall property value without buying new land. It’s a cost-efficient way to expand housing supply under California’s housing law.
5. Start with a Site Review
Zoning, utilities, and fire-access rules vary by city. A quick Backyard Project Fit Report identifies what’s possible on your property before you commit to design or permits.
👉 Ready to see what’s possible in your backyard?