San Francisco · City and County
Commercial Roofing in San Francisco: Flat Roof Repair, Re-Roofs and DBI Permits
Flat roofs on San Francisco apartments, condos, mixed-use and commercial buildings.
- Free roof condition report before December
- Good, better and best bid options
- Certificate of insurance within 24 hours of request
San Francisco's buildings, and why their roofs are different
The California Department of Finance counts 212,514 housing units in buildings of five or more units in San Francisco (January 1, 2026). That's about half of the city's 423,517 housing units, compared with about 30% countywide in Santa Clara County. Add 81,408 units in 2–4 unit buildings and 62,735 single-attached units, in a city of 845,658. Most of it is attached and built lot line to lot line.
What that means on the roof
- Shared parapets and party walls, with flashing that ties into the neighbor's roof
- A roof hatch as the only access
- No laydown area, so materials are hoisted from the street
- Ground-floor storefronts and garages under the roof edge
Where the building types cluster
Fog-belt multifamily in the Sunset and the Richmond; mixed-use corridors across the city; commercial buildings in SoMa and Mission Bay; industrial buildings in Bayview and Dogpatch.
Fog, wind and a December peak: SF weather on flat roofs
NOAA's 1991–2020 normals at SFO put the year at 19.64 inches, with December the wettest month (4.14 inches), followed by February (3.96) and January (3.89). About 85% of the year's rain falls from November through March.
Coastal fog and salt air on the western and bay-facing sides of the city age sheet metal and fasteners faster. The practical result: check coping, counter-flashing and drains in the fall, and expect leaks in December. Book a free roof condition report before then, and see commercial roof repair and leak response if water is already coming in.
Re-roofing permits in San Francisco (DBI)
From SF.gov's "Apply for a reroofing permit":
- A permit is needed before installing, repairing or removing roofing material, with exemptions listed in SF Building Code §106A.2 item 13.
- Online applications are only for licensed C-39 roofing contractors, and only when there are no plans and no structural or decking work. Otherwise it's an over-the-counter (OTC) permit.
- The application asks about hot work (torch-applied roofing), whether the building is a landmark or historic resource that needs Planning approval, and cool-roof compliance for commercial work replacing more than half the roof or more than 2,000 square feet, whichever is less.
- A street-space permit is included for the work, and historic and commercial applications get staff review.
- Fees are published by DBI on SF.gov.
Your roofer should apply; online filing is limited to C-39 contractors.
Title 24 and SF's Better Roofs rules: what applies to a re-roof
Title 24 cool roof and insulation
A qualifying nonresidential low-slope re-roof needs aged solar reflectance of at least 0.63 and thermal emittance of at least 0.75, or an SRI of at least 75, with a CRRC label, and a replacement over conditioned space generally needs R-23 continuous insulation in climate zone 3, which covers San Francisco (BayREN 2025 guide; CEC). See commercial roof replacement for the exceptions. Our Title 24 re-roof guide walks through the trigger, the cool roof values and the insulation rule.
Better Roofs applies to new construction
San Francisco's Better Roofs requirements apply to new construction: nonresidential buildings of 2,000 square feet or more and residential buildings of any size with 10 or fewer occupied floors, permitted on or after January 1, 2017. They require solar on 15% of the roof area or a living-roof alternative (SF Planning, Zoning Administrator Bulletin No. 11). They aren't a re-roof requirement. On a newer building that already has solar or a living roof, the scope has to say how it will be protected, or removed and reset, during the roof work.
Common San Francisco roof problems
Parapet and coping leaks
Shared parapets and coping on attached buildings, aged by fog and salt air.
Ponding at interior drains
Older flat roofs that drain to interior drains, where debris and sagging decks hold water.
Torch-down at end of life
Modified bitumen roofs with open laps, blisters and worn granules.
Leaks over storefronts and garages
Water that shows up in the ground-floor tenant's space, not the unit upstairs.
Skylights and hatches
Curbs and flashing around the openings that give the roof its light and access.
Who we work with in San Francisco
HOA boards & community managers
Board-ready bid packages with good, better and best options, timed around the reserve study.
Property managers
A COI within 24 hours of request and a photo report you can forward to the owner.
Retail and restaurant buildings
Where kitchen exhaust puts grease on the roof, KEE PVC is commonly specified by membrane manufacturers.
Nearby
San Mateo County: south of the city line, Daly City and South San Francisco share the fog belt and the same December rain peak at SFO.
Oakland: across the bay, a different building mix with more small multifamily and a large industrial base. See commercial roofing in Oakland.
Frequently Asked Questions
Yes, in most cases. San Francisco's Department of Building Inspection requires a permit before roofing material is installed, repaired or removed, with limited exemptions in the building code. Only a licensed C-39 roofing contractor can apply online, and only for work without plans or structural or decking repairs. Other jobs need an over-the-counter permit.
DBI takes reroofing permit applications online from C-39 licensed roofing contractors. The permit includes the street-space permit needed for the work, and commercial and historic-building applications get staff review. Fees depend on the project and are published on SF.gov. Torch-applied roofing and landmark buildings add questions to the application.
No. San Francisco's Better Roofs requirements apply to new construction, not re-roofs. They cover new nonresidential buildings of 2,000 square feet or more and residential buildings of any size with 10 or fewer occupied floors. A re-roof still has to meet state Title 24 cool roof rules when the work is large enough.
San Francisco's reroofing permit application asks whether the job involves hot work, so torch-applied roofing has to be disclosed up front. Whether it's the right choice depends on the building, the neighbors and the fire-safety plan. Cold-applied or self-adhered systems and single-ply membranes are common alternatives.
December. NOAA's 1991–2020 normals at SFO put December at 4.14 inches, the wettest month, and about 85% of the year's rain falls November through March. Fall is the time to clear drains, check parapet flashing and fix small defects before the first big storm.
Commercial Roofing Inc. repairs, coats and replaces flat roofs on San Francisco apartment, condo, mixed-use and commercial buildings. The cause is documented with photos, and you get a line-item scope you can forward to an owner or board. Call (408) 770-5992 or request a bid.
Let's get started
Request a bid for a San Francisco building
Tell us the address or neighborhood, the building type and what you need. Bid invites and plans are welcome. For an active leak, call.
- (408) 770-5992Calling is fastest for an active leak