Because the visible leak is not always the real source of the problem. Water can travel through the roofing system before it appears inside, especially around flashing, roof transitions, vents, skylights, and other vulnerable areas. The Cambridge Aucoin page emphasizes diagnosing the real issue before recommending a solution, which is especially important when the damage seems small on the surface. At Aucoin Roofing, leak detection is about finding the cause early so a smaller issue does not turn into larger structural damage.