1601 Monterey duplex conversion adds state ADU at $1.7M in West of Twin Peaks
The Department of Building Inspection issued a $1.7 million change-of-use permit on January 28 for 1601 Monterey Boulevard in West of Twin Peaks, converting a single-family home to a two-family home through the addition of a state ADU at the basement level.
The permit also includes replacement of exterior windows and doors, three new dormer windows at the rear, and new skylights at the roof. Per the permit description, the vertical alterations are exempt from neighbor notifications under Section 311. The two-story wood-frame structure is unchanged.
The site is in the West of Twin Peaks neighborhood, in Supervisor District 7.
- Permit number: 202510076863
- Address: 1601 Monterey Bl, San Francisco 94127
- Neighborhood: West of Twin Peaks (Supervisor District 7)
- Permit type: Additions, alterations, or repairs
- Existing use → Proposed use: 1 family dwelling → 2 family dwelling (change-of-use)
- Existing units → Proposed units: 1 → 2
- ADU: Yes
- Estimated cost: $1,718,690
- Revised cost: $1,718,690
- Filed date: 2025-10-17
- Issued date: 2026-01-28