A roof is a system, not just a layer of shingles. Under them sit underlayment, decking, flashing at every wall, chimney and valley, boots around the pipes and vents along the ridge, and a leak usually starts where one of those pieces fails. Good roof repair in Randolph starts by tracing the water back to where it gets in, since water runs along rafters and decking before it shows up inside.
Most Randolph roofers sort roof problems into three groups: storm damage, wear and age, and installation details that were never right. Wind lifts tabs and breaks the sealant strips, hail knocks granules loose and leaves soft spots, and falling branches puncture the deck. Age shows up as curling, cracking, bald shingles and dried out pipe boots, while bad details show up as leaks at flashing, valleys and skylights no matter how new the roof is.
It helps to know a little about the roof before you talk to a roofing contractor. Write down where the stain or drip is, when it shows up and how old the roof might be. Say what kind of roof it is, whether asphalt shingle, metal, tile, slate, cedar or a flat roof, since the repair depends on the material. The roofer works out the cause; you only need to describe what you see.