ADU Construction in San Francisco: 2026 Complete Guide

By SolidBay Construction SF | Updated 2026

Accessory Dwelling Units have become one of the most popular projects in San Francisco, driven by state law changes that dramatically streamlined approvals.

Types of ADUs in San Francisco

• Garage conversion ADUs — most common in SF
• Basement ADUs
• Attached additions
• Junior ADUs (JADUs) — up to 500 sq ft

ADU Construction Costs in SF

• Garage conversion ADU: $180,000 – $350,000
• Basement ADU: $200,000 – $400,000
• New detached ADU: $300,000 – $600,000+

ADU Permits in San Francisco

Under current California and SF law, most single-family properties can build one ADU and one Junior ADU by right — no discretionary hearing needed. Our permit expeditor handles the entire DBI process.

ADU Timeline

• Garage conversion ADU: 12–18 months
• New detached ADU: 18–24 months

ADU Return on Investment

A well-built ADU in San Francisco can generate $2,500–$5,000/month in rental income and add $300,000–$600,000+ in property value.