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How Wind Causes Damage to Roofs

Wind can cause severe damage on any residential roofing system, to the point where it may require a complete roof replacement. While wind is unavoidable when it hits, understanding how it causes damage can help you make informed decisions on which roofing options are available to you. Oberg Roofing & Remodeling shares an overview of how wind causes damage.

Wind Uplift

Wind uplift is a phenomenon where materials are lifted into a vacuum created by wind. There are two conditions that cause wind uplift: loss of laminar flow and increased wind speed.

Laminar flow is the air that flows over a surface, such as a roof plane. As dictated by the laws of physics, wind will adhere, or laminate, itself onto a surface. On a perfectly level surface, this is fine. If there’s a sharp bend or curve on the surface—the underside of an asphalt shingle or a standing-seam sheet on steel roofs, for instance—the wind follows the same trajectory, creating a pocket of vacuum underneath. If strong enough, this vacuum can pull off roofing.

When wind flowing over a roof changes speed, it results in lower pressure. This usually happens when the wind over the roofing plane hits a wall or another higher roofing plane. The change in pressure creates a vacuum that results in uplift.

Positive Pressure

Positive pressure is easier to illustrate. It’s simply the wind hitting a surface that offers resistance. The wind has to go somewhere, so when it hits a wall, it results in positive pressure, spreading outwards and up. A strong wind hitting your home’s exterior wall can damage the soffit. Wind hitting your roof head-on can pull up entire rows of asphalt shingles. One of the most common signs of positive pressure is the presence of horizontal creases that appear about an inch below the edge of the shingle right above it. It looks like the shingle was folded, because it actually is.

Wind Inflation

When wind finds its way under the roofing material, be it shingles, metal, or single-ply roofing, it can pull up the roofing material. Since most roofing materials are installed in layers, several layers of outer roofing can be removed by a single burst of wind. On a ballasted single-ply roof, wind inflation makes the roof look like a bedsheet left hanging on a clothesline during a windy day.

Looking for roofing companies that offer roofs with high wind ratings? Give Oberg Roofing & Remodeling a call at (320) 204-2303 and (651) 300-0688. You can also fill out our contact form to schedule an appointment. We serve customers in Sauk Rapids, MN and the surrounding areas.