This TPO roof overlay San Francisco case study shows how we stopped active leaks on a two-year-old Bayview flat roof — no tear-off, watertight within a week. A Bayview homeowner at 1582 Quesada Avenue had active leaks over the bathroom and dining nook — on a roof that was only re-done in 2022. Instead of making her pay for a full tear-off twice in four years, Lifetime Roofing & Renovation installed a white TPO overlay directly over the existing flat 3-ply roof for $11,900, sealing every leak in a single membrane and closing the project out within a week of the first call.
A Two-Year-Old Roof, Already Leaking in Two Places
This one-story Bayview home had a flat 3-ply built-up roof installed in 2022 — and by February 2026 it was failing anyway. Water was coming through above the bathroom and over the dining nook, and the aerial photos tell the story: long stripes of white mastic patching criss-crossing the black asphalt surface where previous repair attempts had chased the leaks without catching them. The homeowner was understandably budget-conscious. Having paid for a roof four years earlier, she was clear about one thing: no full tear-off and re-roof. She needed the leaks stopped for good, at a price that made sense for a roof this young.
A White TPO Overlay — Not a Second Tear-Off
Because the 2022 roof was structurally sound and dry underneath — the failures were in the surface plies and patched seams — a TPO overlay was the right call: a single-ply, heat-welded membrane installed directly over the prepared existing roof. The existing 3-ply becomes the substrate; there’s no tear-off labor, no disposal fees, and no days with the house open to the weather. The scope, signed the same day as the first appointment (February 16, 2026), covered full roof preparation — cleaning the surface of dirt, debris, and loose material — followed by the white TPO membrane system.
It’s the same single-ply technology we install on commercial flat roofs, sized for a residential budget: $11,900, all-in. And unlike another round of patches, an overlay replaces the entire waterproofing surface at once — which is what it takes to stop a roof that’s leaking in multiple places. When a roof is failing at one isolated spot, we say so and quote a targeted repair instead; this one needed the full surface.
Signed Same-Day, Watertight Within the Week
The homeowner reached out on February 16; our estimator confirmed the appointment, walked the roof, and had the signed scope in hand by 2 PM the same day. The crew prepped the existing surface first — every bit of dirt, debris, and loose material off the field, because a membrane is only as good as what it’s welded over.
The membrane sheets were then heat-welded into one continuous surface — no adhesives to fail, no seams relying on tar. Every penetration got its own welded detail: new boots on the vent pipes, wrapped flashing at the furnace flue and curbs, and clean terminations at the parapet walls. By February 23 the job had moved to close-out, and the homeowner’s warranty certificate was issued shortly after. When she later reported a stubborn drip near the dining nook, our crew came back under that warranty, ran a full leak test, and documented the findings — because a roof relationship doesn’t end at the invoice.
Before vs. After
| Feature | Before | After |
|---|---|---|
| Roof surface | Patched 3-ply built-up roof, mastic repairs spreading across the field | One continuous heat-welded white TPO membrane |
| Leaks | Active leaks above the bathroom and dining nook | Sealed under a single new waterproofing surface, leak-tested |
| Penetrations | Aging mastic smeared around vents and pipes | New welded TPO boots and flashing details at every penetration |
| Cost approach | Facing a second full roof bill in four years | $11,900 overlay — no tear-off, no disposal, one-week turnaround |
| Heat & sun | Dark asphalt surface absorbing solar heat | Reflective white membrane that sheds it |
| Coverage | Piecemeal patches, no warranty | Workmanship warranty with documented follow-up service |
TPO Roof Overlay San Francisco: Why Flat-Roof Homes Choose It
Walk any block in Bayview, the Sunset, or the Mission and you’re looking at flat and low-slope roofs — built-up asphalt systems layered over decades. San Francisco’s marine layer and wind-driven winter rain find every tired seam, and when a built-up roof starts leaking in more than one place, patching becomes a subscription, not a fix. A TPO overlay breaks that cycle at a fraction of tear-off cost, and the white membrane earns its keep on sunny days too.
If your flat roof is on its second or third round of patches, our San Francisco roofing team can tell you in one visit whether it’s a candidate for an overlay — or just needs one honest repair. See more completed work on our roofing projects page. For most of these homes, a TPO roof overlay San Francisco crews can install in days is the most cost-effective way to stop leaks for good — no full tear-off, far less disruption.
TPO Overlay Questions, Answered
Can you install TPO over an existing flat roof?
Yes — if the existing roof is structurally sound and dry underneath, TPO can be installed directly over a prepared built-up roof. The surface is cleaned of dirt, debris, and loose material, then the membrane is heat-welded into one continuous waterproof layer. That’s exactly what we did at 1582 Quesada Ave, avoiding a full tear-off entirely.
How much does a TPO overlay cost in San Francisco?
This one-story San Francisco home was $11,900 all-in, including full surface preparation. An overlay typically costs meaningfully less than a tear-off and re-roof because there is no removal labor or disposal, and your final price depends on roof size, penetrations, and parapet details — we quote it in writing after a free inspection.
What happens if a leak comes back after the work?
You call us and we come back — that’s what the workmanship warranty is for. On this project the homeowner reported a stubborn drip after installation, and our crew returned, performed a full leak test, and documented the findings under warranty at no charge. Every Lifetime project includes a written warranty certificate.
Flat Roof Leaking Again?
Get an honest answer on repair vs. overlay vs. replacement — with real prices, in writing, after a free inspection. Serving San Francisco and the entire Bay Area.
Gina K. writes about Bay Area roofing for Lifetime Roofing & Renovation, drawing on the team's 16+ years of experience and 1,000+ completed roofs across Silicon Valley.
