Board upholds Zoning Administrator: multistory rear decks are excluded from rear‑yard averaging

The San Francisco Board of Appeals upheld a Zoning Administrator Letter of Determination finding that deck and stair structures are not counted as a rear building wall for rear‑yard averaging purposes.

Sydney Day, the appellant, and architect John Goldman argued that a sizable multi‑story deck and stair structure at an adjacent property on Hattie Street occupies more than half the lot width and rises two stories, and therefore should be treated as a qualifying portion of the building when calculating rear‑yard averaging. Goldman told the board that the code language referring to the ‘‘line of greatest depth of any portion of the adjacent building’’ supports counting such portions and that treating large decks as non‑building faces produces inconsistent and unclear outcomes.

Scott Sanchez, the City Zoning Administrator, and Joe Duffy of the Department of Building Inspection described the department’s longstanding interpretation: rear‑yard averaging considers the building wall that encloses conditioned or habitable floor area, and decks/stairs are treated as appendages or structures, not as the rear building wall. Sanchez said the Planning Department has applied that interpretation consistently and that the code's purpose is to preserve mid‑block open space and limit encroachments. Duffy explained that deck treatment often depends on occupancy and use; in single‑family contexts decks are not considered habitable floor area.

Appellants acknowledged the project’s effect would be modest in their case (about a two‑foot difference) but urged the board to clarify citywide practice. The board considered existing written interpretations and precedent, agreed the department’s past practice and interpretations support the Letter of Determination, and voted to deny the appeal. The Zoning Administrator’s determination stands.