Your fascia board sits right at the roof edge where wind is strongest. When suction pulls on that flat face, tiny nails just cannot hold on. That is how water gets into your house.
Think of your fascia board like a flag on a pole. When wind blows past it, the flat face catches the flow and creates suction - like a vacuum trying to suck the board off the house.
This is especially bad at the roof edge where wind speeds up as it flows over the eave. The fascia sits right in the high-pressure zone where suction is strongest.
Most fascia boards are installed with 2-inch finish nails every 12-16 inches. These nails are smooth and slender - perfect for trim work where looks matter more than strength.
But when 85 PSF of suction pulls on that fascia, each nail needs to resist 25+ pounds. Smooth nails in wood just slide right out!
In Broward County, we use ring-shank nails or screws spaced 6 inches apart instead of 12-16. Ring-shank nails grip the wood fibers and resist pullout 3-4 times better than smooth nails.
Even better: use fascia clips that wrap around the board and bolt to the rafter tails. These metal brackets can resist hundreds of pounds of pull.
Fascia boards at the roof edge in Broward County experience negative (outward) pressures of -65 to -95 PSF depending on the building height and roof zone. Corner fascia can see pressures exceeding -110 PSF. This outward suction tries to pull the fascia board away from the rafter tails.
Fascia boards fail because they are typically attached with only finish nails designed for holding the board in place, not resisting wind loads. When wind creates suction on the fascia face, these small nails pull out. The board peels away, often taking gutters and soffit with it, exposing the roof structure to wind-driven rain.
In high-wind areas like Broward County, fascia boards should be attached with ring-shank or screw-shank nails at 6 inches on center, or screws rated for the design pressure. Some installations use metal fascia clips that wrap around the board and fasten to the rafter tails with structural screws. The connection must resist the calculated outward wind pressure.
When fascia blows off, it creates a chain reaction of damage. The exposed rafter tails let wind get under the roof edge, increasing uplift on the entire roof. Rain enters the attic and walls. The soffit usually follows since it was attached to the fascia. Gutters tear away. This cascading failure can lead to major structural damage.
Calculate exact outward pressures and fastener requirements for your fascia installation. PE-stamped calculations for Broward County permits.
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