How To Find & Fix A Roof Leak /// The source of most roof leaks is hard to find because it originates away from where the leak shows up. In order to find the source of a leak, follow a roofer’s advice and “think like water.” /// Water typically comes in through worn, broken, or missing shingles; where nails have worked loose; or through corroded or poorly sealed roof flashing around vents, skylights, or chimneys or along the intersections of roof planes.