Repair or Replace? How to Know What Your SF Roof Actually Needs

One of the most common questions we get from San Francisco homeowners is whether a leaking or aging roof needs to be fully replaced or whether a targeted repair will do the job. The honest answer depends on age, scope of damage, and the underlying structure — and any contractor who tells you 'always replace' without inspecting carefully is selling, not advising.

If your roof is under 15 years old and the leak is isolated to a single area — a flashing detail, a slipped shingle, a cracked seam around a vent — a targeted repair almost always wins. Patching a single problem area typically costs 5 to 15 percent of a full re-roof and buys real time, often another 5 to 10 years of service life if the rest of the system is sound. We see this constantly with relatively new homes where one bad penetration is the entire source of trouble.

Replacement starts making sense when the symptoms are systemic. Multiple leaks across different roof planes, widespread granule loss in the gutters, curling or cupping shingles across whole sections, sagging in the decking visible from below, or daylight visible from inside the attic all point to a roof that's reached the end of its service life. At that point, repairing one section just shifts the next leak somewhere else, and you'll spend more on incremental patches over three years than you would on a single planned re-roof.

Age is the other big factor. Composition shingle roofs in SF's climate typically last 20 to 25 years; flat single-ply roofs 15 to 25 depending on material and maintenance; metal 40 plus. If your roof is in the final third of that range and already showing problems, replacement is usually the more economical move even when individual repairs would technically hold.

Before committing to either path, get more than one opinion — ideally from a contractor who will quote both a repair and a replacement and tell you straight which they'd actually recommend. A reputable roofer will turn down a replacement job if a repair will solve the problem; that's the single best signal of an honest contractor. If two of three estimates say 'repair' and one says 'replace,' trust the consensus.

Finally, factor in the things repairs can't fix: outdated underlayment, missing ice-and-water shield in critical areas, inadequate ventilation, or framing issues that have been hidden under the existing roof. A full replacement is the only time you get to address those, and on an older SF home they're often worth the investment on their own.