Why Exposed Fasteners Matter
Most fasteners on shingle roofs are protected under the next course of shingles. When a fastener remains visible, such as on base flashing or on ridge caps, it depends on sealant instead of overlap to protect it.
Most fasteners pass through the roof covering and into the roof deckComponents - A roof deck is the structural surface connected to a building’s framing that supports the roof system installed above it. More. When the fastener head is not protected, water can follow the same opening the fastener created unless sealant or a gasket blocks that path. On metal roofs, gaskets are used to prevent water from following the fastener past the roof surface.
The concern is not the visible fastener. The concern is how its protection degrades over time. Sealant and gaskets dry out over time. Routine roof maintenance often includes resealing exposed fasteners to prevent these small holes from becoming big leaks.