Once those colored granules erode, however, the exposed asphalt deteriorates rapidly. The final factor determining the life expectancy of the roof is the thickness of the shingle. As one might expect, thinner shingles deteriorate faster than thicker shingles. Inspect your roof flashing every spring and fall. Roof flashing can be metal, asphalt, rubber, or any suitable material that prevents water from seeping underneath your roofing around chimneys, vent pipes, dormers, or skylights.
Different situations call for different types of flashing.
Modern vent pipes are often flashed with one-piece neoprene or galvanized collars. Older vents may have been repaired with asphalt-coasted membrane and roofing cement. Most professional roofers prefer overlapping pieces of copper around masonry chimneys and alongside dormers. Regardless of the material, flashing can develop leaks. When it does, rainwater and melting snow have a direct route through the wood sheathing to the plaster walls and ceilings below.