Metal siding screw density — field vs perimeter vs corner, and the washer kiss
Exposed panels run ~80 screws/square in the field, tightened at the perimeter and corners where wind concentrates, then scaled by the wind zone (×1.15 high-wind, ×1.30 HVHZ). Drive each screw only until the EPDM washer kisses the panel — over-driving crushes the washer and leaks.
What this diagram shows
Left: an exposed-fastener metal panel elevation showing screw placement at three densities — gray screws spaced through the field at about 80 per square (12 inches on center on the ribs), denser amber screws around the perimeter (about 6 inches on center), and the tightest red screws doubled at the corners (about 4 inches on center), because wind uplift concentrates at edges and corners. A card lists the whole-job wind multiplier the calculator applies: standard wind times 1.0, high-wind or coastal times 1.15, Florida HVHZ times 1.30. Right: a detail of a screw driven correctly, its EPDM washer just kissing the rib to seal while the panel stays free to move (green check), versus an over-driven screw whose washer is crushed and rib dimpled so it leaks (red cross).
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