ADU Rules in Placer County: What You Can Build

California's housing shortage has led to a boom in Accessory Dwelling Units (ADUs), also known as granny flats or casitas. Placer County has embraced this trend, making it easier than ever to build.

What is Allowed?

• Detached ADU: Up to 1,200 sq ft.
• Attached ADU: Up to 50% of the main house size (max 1,200 sq ft).
• JADU (Junior ADU): Up to 500 sq ft, created within the existing walls of the home (e.g., converting a master suite).

Key Regulations (2025/2026)

• Setbacks: Only 4 feet from side and rear property lines.
• Parking: No additional parking required if you are within 0.5 miles of transit.
• HOAs: Homeowner Associations cannot ban ADUs (state law overrides them).

Why Build an ADU?

1. Rental Income: Rents in Roseville for a 1-bed unit average $1,800+.
2. Multi-Generational Living: Keep aging parents close while maintaining privacy.
3. Property Value: An ADU can add $100k - $150k to your property value.

The Cost Reality

Building isn't cheap. Expect to pay $250 - $350 per sq ft for construction. A detached 600 sq ft unit could cost $180,000+. However, the long-term ROI is often double digits.