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A self-tapping screw is a screw that can tap and form its own mating threads in the material (such as metal, wood, or plastic) as it is driven into a pre-drilled pilot hole.
Self-tapping screws require a pre-drilled pilot hole before installation. Self-drilling screws, on the other hand, feature a point shaped like a drill bit, allowing them to drill their own hole and tap threads in a single operation without pre-drilling.
Yes, they can generally be reused, but they may not hold as securely in the same hole during reinstallation, especially when used in softer materials like plastic or wood where the thread path can strip easily.
Self-tapping screws are highly versatile and are commonly used for securing sheet metal, aluminum, plastics, composites, wood, and fiberglass in various construction and assembly projects.
The rubber washers (often EPDM) provide an airtight, waterproof seal. When the screw is tightened, the washer compresses to seal the hole against moisture, preventing leaks and rust on metal roofing panels.
