Commercial Roof Maintenance San Francisco (2026): Systems, Plans, Types & Real Costs

Modified Bitumen — The Workhorse of SF Commercial Roofing

Modified bitumen (APP and SBS) is the most common system on SF commercial and multi-family buildings installed in the 1990s through today. Torch-down, cold-applied, and self-adhered versions.

Where you find it in SF: Mixed-use on Judah, Noriega, Irving, Valencia. Multi-family commercial throughout the Mission, Castro, Sunset, and Richmond. Small commercials throughout the neighborhoods. Replacement systems on older BUR buildings.

What it needs for maintenance:

• Biannual inspection — before and after rainy season
• Seam and lap inspection for lifting or separation (the primary failure mode)
• Flashing inspection at all walls, penetrations, HVAC curbs, and drains
• Drain and scupper clearing — debris accumulation at drains is the leading cause of ponding and subsequent membrane failure
• Blister and delamination identification
• Surface condition assessment (granule loss on cap sheets, UV oxidation)
• Flashing resealing and repair at detected failure points
• Post-storm inspection after significant atmospheric river events

SBS vs APP in the SF climate: SBS (rubber-modified) handles the fog-belt thermal cycling better than APP (plastic-modified) in most applications. More flexible at lower temperatures, which matters in the marine climate. We specify SBS on most SF commercial reroofs.Metal Roofing on Commercial Buildings

Standing seam metal, corrugated metal, and older commercial metal panel systems appear on industrial, warehouse, and some retail commercial buildings in SF. Bayview, Dogpatch, SOMA, Potrero Hill.

What it needs for maintenance:

• Annual inspection of fastener condition — screw-fastened panels lose fastener integrity over time, especially in the salt-air environment
• Seam and panel joint inspection for separation or lifting
• Sealant at penetrations and transitions
• Rust assessment on steel panels — galvanizing or coating condition
• Gutter and downspout clearing
• Flashing at wall transitions and equipment curbs

Standing seam vs exposed fastener maintenance: Standing seam has no exposed fasteners and significantly lower maintenance burden. Exposed fastener panels need fastener inspection and replacement on a regular cycle. The salt environment in coastal SF neighborhoods accelerates fastener corrosion on steel-fastened systems.