Some commercial roofing materials have better wind resistance than others, but—and this may be seem counter-intuitive—no single roofing material always survives high winds, nor does any one type always fail. Predicting the wind resistance of an applied commercial roofing material is tricky, though some general trends emerge from BELDON® Roofing Company’s decades of experience.
How Wind Damages Commercial Roofing
To understand the uncanny way high winds can destroy your building’s roof, you have to recall an airplane’s wing. Bernoulli’s Principle reveals that a change in air pressure above and below a surface will cause the surface to lift if the lower pressure is above, and the higher pressure is below. When wind passes quickly across a roof, pressure drops; the higher pressure inside the building pushes outward, in wind uplift. Bluntly speaking, wind does not suck a roof off a building; pressure inside pushes it off.
Strong adhesion and lowering the roof deck’s pressure are key to keeping any roof—metal, single-ply, modified bitumen, built-up, you name it—attached. Fighting your roofing contractor’s best efforts to keep your roof mechanically adhered or glued down are some trouble spots:
- Scuppers—Because through-wall openings will increase wind’s speed, some roofs start failing at these spots from the strong pressure differential
- Edges—Strong edges hold down strong roofs. Perimeter edge metal should have continuous cleats and be sized so the longer the vertical face of the metal, the thicker its gauge. Roof terminations are likely points of origin for wind-related failures of commercial roofing
- Add-ons—Small rooftop pieces carried by the wind can scour the roof, and large items (HVAC systems, satellite dishes, billboards) can lift out roof sections
Most Likely To…
Conventional roofs using heavy materials naturally handle wind best because of a combination of weight and how the roof is connected to the rest of the building. Conventional built-up roofing (BUR) and modified bitumen fully adhered to full concrete roof decking hold up well. Gravel-coated BUR performed best overall because the embedded gravel prevented gouging and scouring.
Single-ply membranes can sustain more tears and gouging. Fully-adhered (glued) single-ply have greater wind resistance than mechanical fasteners, because if the wind finds even a single weak fastener weaker, a domino effect ensues.
Choose BELDON® For Your Home’s Needs!
Have some questions or need some roofing advice? Need to schedule a service? Give our team at BELDON Roofing Company a call.