A leaking flat roof on a mixed-use building. An aging membrane over occupied offices. A re-roof you need to plan around tenants who can’t close. Send a few details and one vetted, licensed San Francisco roofer gives you a straight answer on what it takes.
Tell us the building type, the roof system if you know it, and whether it’s occupied. In this city, commercial work is as much about scheduling around tenants as it is about the roof.
Flat, occupied, and unforgiving
The buildings along the city’s commercial corridors wear a big low-slope roof: TPO, modified bitumen, or an older built-up membrane going brittle. Ground-floor retail with flats above in Noe Valley and the Mission. Light-industrial and studio space in Dogpatch and the eastern SoMa blocks. Small apartment buildings everywhere in between. That roof carries HVAC units, exhaust fans, and a maze of penetrations, and it drains through internal drains and scuppers that clog with leaves and pigeon debris. When it fails, it is rarely one tenant’s problem. Water crosses the deck and drops into several units, a business below, a room full of inventory.
The cheapest commercial bid is usually the one that skipped the drains and the flashing details. You meet that saving again in January, in someone’s ceiling.
The other reality is that the building is working while you work on it. A restaurant cannot go dark for a week. Tenants need the door. A property manager is answering to owners about cost and disruption before the first roll of membrane arrives. Good commercial roofing here is planned around all of that: staging so businesses keep running, sequencing the roof in sections so no part sits open to weather, and being straight about what can be repaired versus what has to be replaced. On a re-roof, Title 24 pulls in a cool-roof membrane on most low-slope commercial roofs, and the permit runs through the Department of Building Inspection.
What drives a commercial estimate here
Two buildings the same size can price miles apart. Access, occupancy, and how far the membrane has gone do most of the work. Rough 2026 ranges for SF low-slope commercial:
| Scope | When it’s the right call | Rough cost (2026) |
|---|---|---|
| Targeted seam or flashing repair | Membrane sound, failure is local | $800–$4,000 |
| Drain and scupper correction | Ponding, water backing up under the membrane | $1,500–$6,000 |
| Silicone or acrylic recoat | Membrane worn but intact, buys 8–15 years | $4–$8 / sq ft |
| Full tear-off and TPO/PVC replacement | Membrane failing across the roof | $12–$22 / sq ft |
| HVAC curb and penetration reflash | Leaks clustered around rooftop equipment | $600–$3,000 |
Repair or replace, without the sales pitch
The honest answer turns on the membrane’s overall condition, not the leak in front of you. A roof that is sound apart from a few localized failures can be repaired or recoated and run for years at a fraction of replacement cost. A membrane that is failing across the whole field turns repairs into a monthly expense, and a planned replacement becomes the cheaper path once you count the callbacks. An owner budgeting a building deserves to know which of those two roofs they actually have, not just the number that closes the deal fastest.
Common questions
Can the work happen without closing the businesses below?
Usually yes, with planning. The roof is worked from above, so tenants below generally keep operating. It takes staging the access, protecting the interior, and sequencing the roof in sections so nothing sits open to weather. Noise and short access interruptions are the real trade-offs, and they get communicated ahead of time rather than sprung on a tenant mid-job.
A leak is hitting more than one unit. How do you find the source?
Water enters at one failed point: a seam, a penetration, an HVAC curb, a drain backing up. Then it spreads across the deck and drops into several units well away from that entry. Finding it means working the roof systematically, drain by drain and seam by seam, instead of patching wherever the latest drip was reported. Fix the true source and every downstream leak stops at once. Chase the drips and you are back next week.
Does a re-roof trigger Title 24 cool-roof requirements?
On most low-slope commercial roofs in San Francisco, yes. A full replacement generally has to meet Title 24, which in practice means a reflective cool-roof membrane, and the job pulls a DBI permit. It is worth knowing before you budget, because it shapes the membrane choice. This is general information, not code or legal advice, so the specifics for your building get confirmed when the roof is scoped.
Send your San Francisco commercial roofing details
Tell us the building type, the roof system, and whether it’s occupied. You’ll get a straight read on the repair-or-replace decision, how the work would stage around tenants, and a realistic cost picture, with no pressure to book.
No cost, no obligation. Just a clear answer from the roofer who’d actually do the work.