At Exterior Contractor we get allot of phone calls about roof leaks. Water is coming down either the inside or outside of the chimney, We always check the roof and flashing first for installation and maintenance issues, but more often the leak is due to the chimney cap or siding. The flashing ties the side of the chimney together with the roof material by being bent at an angle and then woven and overlapped with the roofing material. If any of the flashing overlaps, roofing materials and flashing isn’t installed correctly or is old and failing, then the system usually needs to be torn out and reinstalled. However, at the point where the flashing ties into the brick or stone chimney, there is a caulk join that periodically needs to be re-caulked so the leak might simply be a maintenance issue.