Credit: Illustration: Matt Wood

Leaks, says Dan O'Connor, rarely stump him. His first question to homeowners is: How old is the roof? His second: Does it leak every time it rains, or only sometimes? If the roof leaks with every rain, says the owner of O'Connor Residential Repair, in Cleveland, “I know there's a hole in the roof.” If it only leaks intermittently, that could be a siding or window problem involving wind-blown moisture. O'Connor makes a point of taking the homeowner up into the attic to see if sheathing is moist or rotting and to explain the importance of proper ventilation. Then comes the $20,000 question: repair or replace?

NORTH TO THE LEAK At one point Brian Atkins, owner of South County Roofing, in Lake Forest, Calif., decided to focus his company's efforts on investigating and repairing leaks, which is now 40% of his business. Many of the roofs Atkins fixes are concrete tile. His method is to stand directly beneath the leak inside the house, then locate its exact counterpart on the roof. Finding that leak, though, most often requires a trip to the attic, where water's path is marked by a telltale trace of dried dust and dirt across the plywood decking. “On OSB, it's harder to spot,” he says.

If Atkins sends a salesperson, the company's procedure is to photograph the roof from the outside, “so I can see steepness and accesses,” Atkins says, and to also get pictures of the leak from inside.

TOUGH CALL Whether to fix a leaking roof or to replace it is a daunting decision for homeowners. Jeff Petrucci, owner of Bloomfield Construction, in Bloomfield Hills, Mich.,, says that, increasingly, his roofing work is repairs because competitors often aren't interested in replacing chimney flashings or venting a roof properly.

Roofers such as O'Connor and Atkins advise homeowners to consider the age of the roof and the type of roofing material, whether faulty installation is a cause, and how long the clients plan to live in the house.

O'Connor says that, in his market, 3-tab shingle roofs supposed to last 25 years typically last 22. “I know that if that roof is 18 years old, we're going to be talking about a new roof,” he says. On the other hand, “once you break it down,” Atkins says, “repair often turns out to be the best way to go.” He provides an analysis based on photos, roof life expectancy, and the cost of a re-roof versus the cost of repairing current problems. If the cost of repairs exceeds 30% of the cost of a new roof, a new roof may be the way to go. “If you're only going to live here another five years,” he tells homeowners, “you're giving the next homeowner an $11,000 bonus.”