August 18, 2016

Does Metal Roofing Really Perform Better in Severe Wind Storms?

Here in New Orleans, we have all seen first hand the devastation and roof damage our beloved climate can produce. In extreme weather events, the roof is a terrible place to be for all product genres. Does metal roofing really perform better than other products? Let’s take a look at the factors involved. It’s important to understand that, in a hurricane or other windstorm, there are many things that happen which affect the roof.

1. Of course, you have actual physical wind-speed blowing into the roof from some angle. This wind puts strain on the metal panels as it hits them but, sometimes even to a greater degree; it puts uplift pressure on the backside of the roof.
2. Next, you can often have structural movement occurring which will impact roof performance – some homes are built better than others to withstand this. Structural movement can cause roof panels to disengage, particularly if they were not designed to allow for it.
3. Additionally, improper attic venting can cause attics to literally explode. No roof covering will be able to handle that. And, of course, windblown debris striking the roof can compromise its performance as well.

Metal Roofing: The Bag Test

In order to verify their wind resistance, metal roofing products are subjected to uplift tests which simulate actual wind occurrences. This is done through what is called the “bag test”. With some variations, a section of roofing is installed in a laboratory with plastic bagging between the metal and the roof decking. This plastic bagging is then filled with air pressure to determine at what point the metal roof panels disengage. The point of disengagement can be used to approximate a failure point in terms of wind speed. Some metal products have actual mechanical interlocks between the panels. These products, if properly designed and installed, will often perform better in uplift tests than will overlapping panels or panels with a “slip lock” rather than a true interlock. Some products with overlapping panels, though, will have fasteners driven right through the overlap and that can also make them perform very well.

Metal Roofing vs. Wind: The Benefits

Aging is an important factor to remember when considering the wind performance of any roofing material. Many roofing materials soften or become brittle with age. As that happens, their ability to withstand extreme winds lessens. Metal products, on the other hand, retain their strength and wind resistance very well as they age. A 30-year-old metal roof will likely withstand wind the same as a brand new metal roof; most other roofing material doesn’t come close to this ability. For all of these reasons, property owners in wind-prone areas are increasingly turning to metal as their roof system of choice.

The Bottom Line: Metal Protects

Metal roofs offer our New Orleans homes great protection from wind. You can learn more by watching this short video. Your local metal roofing experts, Middle South Systems wants to protect your home.