What actually goes wrong
Debris. Twice a year in a neighbourhood with mature trees, more under a redwood or a liquidambar. A blocked gutter in the first real storm of the season is the single most common call in this trade.
Backfall. A gutter that slopes the wrong way holds water, sags under the weight, and eventually pulls its hangers out of the fascia. Visible from the ground as a bowed line and as standing water hours after rain.
Undersized or too few downspouts. A long run with one outlet cannot move what a San José winter storm puts on it. Overflow at the middle of a run usually means outlets, not blockage.
Discharge against the house. The one that costs real money. Water leaving a downspout at the foundation goes under the slab or into a crawlspace; the fix is an extension, a splash block or a proper underground line, and it is trivial compared with what it prevents.
Rotted fascia. The endgame of the first three. Once the board is soft, the gutter has nothing to hang on, and the repair has become carpentry.
What it costs around here
Published Bay Area pricing: seamless aluminium gutters $8–$15 per linear foot installed; downspouts $30–$75 each installed, with a typical house needing four or five, so $220–$625 for the set; and underground drainage lines $150–$350 per downspout where discharge has to be taken away from the building. Cleaning is a fraction of any of that and is the maintenance that prevents most of it.
When to clean rather than replace
A gutter that overflows in the first storm and behaves for the rest of the season was blocked, not broken. A gutter that holds water on a dry day, sags visibly between hangers, or drips along its back edge onto the fascia has a fall or a fixing problem, and cleaning it changes nothing. The distinction is worth making before agreeing to a replacement run — one is an afternoon's maintenance and the other is a linear-foot price along the whole house.
Seams are the third case: sectional gutters leak at joints as they age, which is why seamless runs are quoted at all, and a house with three leaking joints per side has usually reached the point where replacing beats resealing.
Where gutters are genuinely the roof's problem
Ice is not a factor here, but two things are. A gutter packed solid can hold water against the drip edge and back up under the first course of shingles — real, and a genuine roof issue when it happens. And a downspout discharging onto a lower roof, rather than into its own gutter or a leader, concentrates flow on one strip of shingle and wears it out early.
What to send
The gutter line from the ground along each side of the house. Anything overflowing, during the rain if you can. The bottom of each downspout, and where the water ends up. Fascia boards that look stained, swollen or soft. From a window is fine; from the roof is not — there is nothing about a gutter worth a ladder.
Figures are published prices for this region from 2026 cost surveys and local firms, shown as market context and not as a quote.