Flat Roofing San Francisco — Torch Down, TPO & Modified Bitumen Experts

Commercial roofing San Francisco businesses trust — new installs, repairs, flat roof systems & waterproofing. Licensed, insured.

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Torch Down, TPO & Modified Bitumen Experts

Walk down almost any residential block here and look at the roofs, not the fronts. Flat, most of them — Victorians up front, flat roofs on top. Flat roofing san francisco properties need isn’t a niche service, it’s the default. We install and repair torch down, TPO, and modified bitumen across the city — most weeks, it’s the bulk of what our crews do.
Searching torch down roofing, ponding water, or why your flat roof needs constant attention? You’re in the right place. Quick note first: a flat roof and a shingle roof are basically different trades. A great shingle roofer isn’t automatically good at torch down — the skills barely overlap.

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Torch Down Roofing San Francisco — Installation & Repair

Torch down gets requested more than anything else we quote. It’s the standard on most of San Francisco’s older flat roofs, so a lot of our calls are replacing an existing torch down roof with another one.

Torch Down Roofing
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Torch Down Roof Coating
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What Is Torch Down Roofing?

Torch down — sometimes called torched roofing or torch applied roofing — is a modified bitumen system applied with an open flame. The underside melts and bonds to the layer below when heated. Done right, you get a fully sealed, watertight membrane. Done wrong, you get bubbling, weak seams, and early failure.

Torch Down Roofing Material & Installation Process

Old roofing comes off, or in some cases stays as a base layer if the deck’s sound. A base sheet goes down first. The cap sheet gets heat-welded on top, seam by seam, with every penetration sealed individually. It’s slow, precise work — not a weekend DIY project, given the open flame.

Torch Down Roof Coating & Rejuvenation

Not every aging torch down roof needs a full tear-off. If the membrane’s sound but UV-worn — cracking, faded, granule loss — a coating can add years of life for a fraction of replacement cost. It’s maintenance, not a miracle fix, and we’ll tell you honestly when it’s too late for that option.

How Much Does Torch Down Roofing Cost?

Depends on roof size, how many old layers come off, deck condition, and roof complexity. Multi-layer tear-offs cost more than a clean single-layer job. We give real numbers after a free inspection, not a phone estimate — square footage alone doesn’t tell the whole story.

Flat Roof Contractors San Francisco — Systems We Install

Torch down isn’t always the right call. Depends on the building, the budget, and what’s already up there.

TPO Flat Roofing

Single-ply, heat-welded, reflective. TPO’s become the go-to for a lot of newer flat roof installs, residential and commercial. Handles UV well, and the reflective surface helps with cooling costs — homeowners notice it on south-facing additions especially.

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Flat Roof Installation

New installs need proper slope built into the deck or insulation, correct insulation for the building’s use, and materials matched to how the roof actually gets used — foot traffic changes the detailing needed.

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Modified Bitumen Roofing

Torch down actually falls under this category — modified bitumen can be torch-applied, cold-applied, or self-adhered. Multi-layer, proven, and a big part of San Francisco’s flat roof stock for decades.

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Flat Roof Repair

Most repairs come down to a short list — an open seam, a puncture, pulled-away flashing, or ponding water that’s found a weak spot. Caught early, it’s a same-visit fix. Ignored, it turns into deck damage.

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Flat Roofing San Francisco — Why It’s Different Here

Flat roofing behaves differently here than in a drier, sunnier climate. Worth understanding before picking a material.

Best Flat Roof Materials for San Francisco’s Climate

The fog is the main factor — constant moisture, rolling in most nights, gone by mid-morning, repeat. Materials built for moisture cycling — quality TPO, properly installed torch down, UV-resistant modified bitumen — hold up better here than systems designed for drier climates.

Flat Roofing San Francisco — Why It’s Different Here

A “flat” roof isn’t actually flat — it needs a slight slope, or water just sits. Ponding water kills roofs fast, since standing water finds weak seams and UV exposure breaks down a wet membrane faster than a dry one. The fix is usually tapered insulation to correct slope, or clearing a drain that’s been undersized for years.

Standing water gone within 24–48 hours after rain is normal. Still sitting there after three or four days, especially in the same spot every time — that’s a drainage issue worth fixing before it becomes a leak.

FAQs About Flat Roofing & Torch Down Roofing San Francisco

It’s a flat roofing system made of modified bitumen sheets, applied by heating the underside with an open flame torch until it melts and bonds to the layer beneath it. The result is a fully sealed, seamless-feeling waterproof membrane — it’s been a standard choice for San Francisco flat roofs for decades, and for good reason.

Usually by correcting the slope — adding tapered insulation to create proper drainage where there wasn’t enough before — and making sure drains are clear and appropriately sized for the roof area. In some cases a roof coating or localized repair handles it if the ponding’s minor and the membrane’s otherwise in good shape. We’ll also check whether an existing drain is simply undersized for the roof’s actual catchment area, which happens more often than you’d think on older buildings that have had additions or reroofs over the years without anyone revisiting the drainage math. Left unaddressed, ponding water is one of the more reliable ways to shorten a flat roof’s lifespan, so it’s worth fixing at the source rather than just patching the same spot every year or two.

Fifteen to twenty years with proper installation and regular maintenance. Coating an aging roof before it fails can stretch that further, but only if the membrane’s still structurally sound underneath.

Fewer than shingles, mostly grays and whites for reflectivity, though some granulated cap sheets come in limited color options. Most flat roofs aren’t visible from the street anyway, so function usually wins over color choice here.

Rates shift based on material, roof size, layers coming off, and deck condition — there’s no single number that applies across the board, and anyone quoting a flat per-square-foot price without seeing the roof first is guessing. Rates have also crept up over the past couple years along with material and labor costs generally, which is part of why a lot of homeowners are asking this question right now instead of assuming last decade’s pricing still applies. A free inspection gets you an actual number based on your specific roof, not a rough average.

Torch down is heat-welded modified bitumen — durable, proven, been around for decades. TPO is single-ply and reflective, better for cooling costs. Which one’s right depends on your budget and how the roof gets used.

Sometimes, if the deck’s in good shape and local code allows it. We check during the inspection — piling on top of a failing roof just hides the problem, it doesn’t fix it.

Depends on the roof’s condition. Coating works well on a sound membrane that’s just UV-worn. If there’s already deck damage or failing seams underneath, coating just delays the real fix.