Yesterday's wind storms in the Louisville area and across Kentucky produced damaging winds ranging from 50-mph gusts to tornadoes with over 100-mph winds. The most common damages caused by winds in these ranges are downed tree limbs and roof damages. Homeowners all over the commonwealth woke up to the unsettling task of picking up shingle pieces in the yard. This was a storm to be repeated many times over in the coming spring months. Why do asphalt shingle roofs blow off so easily, and do metal roofs fare any better?
Asphalt shingles, the most common residential roof, offer several means of failure when facing high winds. The most common issue is that the seal between layers of shingles is broken and the shingles either lift up or break off. Today's shingles are made with much less petroleum content than in years past, and as a result they are more brittle, and less "sticky," than they used to be.
Metal roofing on the other hand should not rely on tar, sealant, or goop to hold the roof together. Hidden fasteners and interlocking mechanical flanges take the place of stick-together adhesives, and the result is roofing that is much more wind-resistant. For this reason metal roofing is common in the gulf coast region, where hurricane-force winds can be expected (although we learned in 2008 that Louisville is not immune to hurricanes!).
Not only is metal more wind-resistant when first installed but especially as the roof ages. Asphalt shingles will continue to dry out, become more brittle, curl and crack as they age and the sun bakes the oils out of them. Metal roofing is not subject to these changes and should be just as wind-resistant 50 years after installation as it was on the day it was completed.
Homeowners particularly at risk for wind damage are those most exposed to prevailing winds. Homes situated on hills, or with little wind-cover, or in the trough of a natural valley that directs wind currents...all of these can feel the fiercest effects of wind damage. But it's surprising how many homeowners bring up excuses like these for roof failure when in fact the asphalt shingle roof is just a failure-prone, cheap way to cover a roof.
While the up-front investment of metal roofing is higher (2-3x or more depending on the system chosen), homeowners who plan to stay in their homes for the long-term will benefit from that higher initial investment by not having ongoing maintenance and replacement costs after repetitive spring storms like these.
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