When clients call to report a leaking roof, they want answers — and repairs — fast. Here are a few pointers on the likeliest causes of leaky roofs.

Age Matters After he puts on his roof-leak detective hat, sales manager Mike Farina of State Roofing in Monroe, Wash., thinks first about age and pitch. Age matters because ridge caps are more likely to be missing in an older roof, Farina says, and tar-and-gravel roofs tend to have short lives. Even cedar shakes can deteriorate eventually to the point where they can't keep a roof waterproof. Low-pitched roofs are more prone to permit standing water in one area, making leaks more likely.

Farina also checks chimneys, valleys, and skylights. Chimney flashing may need to be replaced. Sometimes the chimney itself needs repointing. Flashing at valleys and around skylights are also likely suspects. “Many manufacturers don't offer enough elevation in the flashing from roof to skylight,” Farina says, especially if the roof is metal. He points the finger at improper installation and deterioration in flashing and frames as two other culprits.

Suspect Seasons The first question Charlie Fiantaco, president of Fiantaco Construction in Sterling Heights, Mich., asks is, Which season is it? In winter, Fiantaco immediately suspects ice damming. The rest of the year, he has a followup question: When does the roof leak — with every shower or only with a heavy rain and lots of wind? If a roof leaks even in a light rain, he'll look for a hole or a shingle missing. If it takes wind to blow rain in, he'll look for flashing problems.

Like Farina, he wants to know a roof's age. Most homeowners don't bother to replace chimney caps, which can permit leaks eventually.

Culprit Catalog “Ninety-eight percent of all leaks occur around pipes, flues, and chimneys, and in valley areas,” says Michael Wolford, commercial sales manager at ProSource Roofing, based in Centerville, Ohio. Improper flashing or a hole usually is the problem, Wolford finds.

In warmer climates, he says, the wind hits vent pipes repeatedly, causing them to move a little. That makes enough space between a pipe and the surrounding materials to let water penetrate. In colder areas, freezing and thawing create the same effect.

Unusual causes of leaks do crop up. A Fiantaco crew was checking on a small hole near a chimney when a swarm of bats swooped out. “You should have seen the guys running for the ladder.”