Water stains bloom on a ceiling tile. A facilities manager sends a roofer up, and the roofer finds nothing. The stain spreads after the next storm. Every missed storm pushes water deeper into insulation, decking, and drywall. On a flat roof, water can travel dozens of feet from the breach before it shows indoors. Electronic leak detection ends the guessing. It locates the exact hole, seam gap, or pinprick without cutting, drilling, or flooding the roof. This guide explains ho