Your gable roof has two vulnerable rake edges running up to the peak. Wind rushing up that slope creates massive uplift right where your shingles have the least support.
Imagine wind as a car racing up a ramp. As it climbs the slope of your gable roof, it speeds up. When it reaches the rake edge, it has nowhere to go but up - creating intense suction that tries to lift your shingles right off.
The rake edge runs the entire length of the slope with no support underneath. It's just shingles hanging over empty air, held by nails alone.
Where the rake edge meets the ridge peak, two airflows collide. Wind coming up both slopes of the gable meets at the top and creates a vortex - a spinning pocket of extreme low pressure.
This Zone 3 corner can see pressures 50% higher than the rest of the rake. It's where shingle peel-back usually starts during hurricanes.
In Palm Beach County, rake edges need metal rake trim fastened every 4-6 inches with ring-shank nails. The last row of shingles gets sealed with roof cement to bond them to the metal.
Some roofers install rake edge clips that wrap around the trim and anchor into the roof deck. These clips can resist over 100 pounds of uplift each - critical for Zone 3 corners.
Rake edges along gable ends in Palm Beach County experience uplift pressures of -75 to -110 PSF in the high wind zone. Near the ridge peak where the two rake edges meet, pressures can exceed -130 PSF. These pressures are higher than the eave edge because wind accelerates as it flows up and over the gable slope.
Gable roofs have exposed vertical wall surfaces at the gable ends that catch wind like a sail. This creates additional pressure on the roof structure and makes the rake edges more vulnerable. Hip roofs slope down on all four sides, presenting a more aerodynamic shape that reduces overall wind loads by 20-30 percent.
Rake edges in Palm Beach County should be secured with metal rake trim fastened every 4-6 inches with ring-shank nails or screws. The last row of shingles along the rake should be sealed with roof cement. Some installations use metal edge clips that wrap around the rake board and anchor to the roof deck for additional wind resistance.
Zone 3 is the roof corner zone where the rake edge meets the eave or ridge. This small area at each roof corner experiences the highest wind pressures on the entire roof - often 2-3 times higher than the field zone. In Palm Beach County, Zone 3 pressures commonly exceed -120 PSF and require the strongest attachment details.
Calculate exact wind pressures for every zone of your gable roof including critical Zone 3 corners. PE-stamped calculations for Palm Beach County permits.
Calculate Rake Edge Wind Loads