Three-year-old roof, leaking chimney: where the water usually gets in

Start with the metal. A chimney needs step flashing, one L-shaped piece woven in with each shingle course, and counterflashing set into the masonry that laps down over it. Jaspector's guide to the IRC chimney rules says counterflashing has to sit at least an inch into a mortar joint or a reglet cut with a saw; a bead of caulk across the face is the defect inspectors find most often. Braga Brothers Roofing describes a callback it sees again and again: new shingles go on, the old flashing stays, and the new roof leaks at a 20-year-old detail.

Next, the back of the chimney. IRC Section R903.2.2 requires a cricket, a small peaked diverter, on the ridge side of any chimney more than 30 inches wide measured across the slope. Without one, water and debris pond against the back face. This Old House prices a framed cricket at $700 to $1,300, The Roofing Brief reported, and it costs much less to add while the deck is open during a reroof.

Water running down stone below the eave may have entered higher up, through a cracked crown, open joints or the cap, and traveled inside the chimney. Braga's guide notes that chimney water rarely shows up where it got in. Before anyone caulks, check the attic decking and rafters on the uphill side, then look for rust streaks, lifted metal or heavy caulk at the flashing line.

Who pays depends on the paperwork. GAF's standard shingle warranty, for example, does not cover workmanship; only its Silver Pledge and Golden Pledge tiers, sold through certified contractors, cover misapplied flashing at chimneys. Everything else falls to the roofer's own warranty and the contract. In Florida, Chapter 558 requires written notice of a defect at least 60 days before a lawsuit; the contractor can inspect within 30 days and must answer in writing within 45.