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Zone 2: The Roof Edge
Watch wind flow separate at the roof edge and create strong suction forces along the perimeter.
Why Roof Edges Get Extra Suction
Imagine blowing across the top of a piece of paper. The paper lifts up because fast-moving air creates lower pressure above it than below. The same thing happens at roof edges, but much more dramatically.
When wind flows up the side of a building and hits the roof edge, it can't make a sharp turn. Instead, it "separates" from the roof surface and creates a turbulent bubble. Inside this bubble, the pressure drops significantly, creating strong suction that tries to lift the roof.
The Waterfall Analogy
Think of water flowing over a waterfall. The water doesn't stick to the rock face - it separates and falls freely. Wind does the same at roof edges. This separation creates a zone of chaotic, low-pressure air that pulls upward on your roofing materials.
In Monroe County, Florida, Zone 2 edge pressures can reach -53 PSF or more. That might not sound like much, but spread across a 4-foot wide edge strip that runs the entire perimeter of your roof, you're looking at thousands of pounds of uplift force trying to peel back your roof like a banana.
This is why building codes require extra fasteners and stronger underlayment at roof edges. It's not just about the corners (Zone 3) - the entire perimeter needs special attention to survive hurricane winds.
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Get accurate Zone 2 values for Monroe County roofing projects
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