Red Bank and Little Silver both have a median house built in 1958, and in Long Branch 24 percent of homes went up before 1940. A roof on a house that age is rarely the original. There may be a second set of shingles under the top one, and under both of them, planks instead of plywood.
Head inland and the houses get younger. The median house in Howell dates to 1985, in Marlboro to 1987, in Holmdel to 1988 and in Tinton Falls to 1991. A house built in the late 1980s or 1990s may still be on its first roof, and shingles that age are often near the end of their life. Out there the question is how the one layer and the wood under it have held up.
Near the ocean the weather adds its own wear. The State Climatologist describes the shore as a zone where land and ocean weather fight it out day to day, and nor'easters come through most often between October and April. On a roof, that means rain pushed sideways under the shingle edges, salt air on nails and flashing, and wind lifting shingles at the eaves and the ridge.
So a Monmouth County roof gets priced from on top of it. We go up when it is safe to, check the attic, and look hardest at the edges and the ridge.