How Much Wind Can a Metal Roof Withstand in London ON?

Every London ON homeowner is worried about the next big storm to hit home. However, it's not always a severe rain or snowstorm that will damage your metal roof. You may be surprised that winds can get extremely strong in the area especially during summer and fall. The question remains: how much wind can a metal roof withstand?

Wind damage is something that occurs nationwide, not just in Ontario. Canada's climate often sees it dealing it with strong-winded hurricanes capable of blowing off metal roofs from homes. However, if you know how much wind can a metal roof withstand, then you can find the right roofing material that won't even budge during the strongest of storms.

It may sound impossible because metal roofs are lighter than other roofing materials. However, Whirlwind Steel has an explanation about the wind resistance of metal roofs below.

How Much Wind Can a Metal Roof Withstand: Factors to Consider

Was the building engineered specifically for your geographic location? 

Metal buildings are not one-size-fits-all entities. A building constructed in California must be built to meet more rigid seismic codes while a building in Oklahoma or Kentucky should be designed to outlast tornadoes. Make sure that your metal building plans are engineered to withstand both typical and extreme weather patterns in your area. We recommend meeting with your local building department to become familiar with the building codes in your area. Metal building manufacturers will also work with you to ensure your metal roofing products are wind resistant.

Is the roof installed via the manufacturer's recommendations?

Metal roofs have the highest strength to weight ratio of any roofing material available. However, that ratio is entirely dependent on the quality of their installation. In a FEMA publication touting the advantages of metal roof systems in high-wind areas, several examples of failed metal roofs are shown. In every case, it was the installation methods - not the materials or the design - that were the problem. If your roofing contractor is not familiar with metal roof systems or the wrong materials are used, your metal roof will not perform as it was designed. Thus, you should be careful to... (Continued)

How much wind can a metal roof withstand? Most London ON homeowners think of an airplane, which is completely made of metal. However, this is a lost comparison. Aluminum is a roofing material with the least wind resistance than steel or copper. Indeed, it can bend and blow off easier, but it does not represent metal roofing in general.

What are metal roofing manufacturers doing about wind damage to metal roofs? North Carolina Metal Roofs has an excellent article that explains what "The Bag Test" and why metal roofs are excellent when it comes to preventing wind damage not just to your roof but your entire property too.

How Much Wind Can a Metal Roof Withstand: Simple Tests

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... (Continued)

Knowing how much wind can a metal roof withstand even in the harshest of windstorms isn't enough. In fact, the property roof design rather than the material plays a big role in having superior protection during windstorms. In this section, we will dive a bit into some basic architecture. However, by understanding the design's major role in preventing wind damage, you can understand best why metal roofs play the best role in this aspect.

MBCI has an excellent post that explains how designers and London ON's most reputable roofing contractors conducting wind damage repairs and replacement services perform their tests, set up their analytics, and other processes enabling them to improve a roof's condition against wind damage.

How Much Wind Can Metal Roofs Withstand: Roof Design Calculations

Calculating Wind Loads

Wind loads are based on the design wind speed (which is based on the geographic location of the building), height of the roof, exposure category, roof type, enclosure classification and risk category.  The height of the roof, and exposure and risk categories are factors that are used to convert design wind speed to an uplift pressure.  Wind speed maps and the rules to calculate wind pressures are found in Section 1609, Wind Loads, in the 2012 or 2015 IBC.  The information is based on an engineering standard written by The American Society of Civil Engineers, “ASCE 7-10, Minimum Design Loads for Buildings and Other Structures.”

Defining Exposure Risk Category

Exposure categories relate to the characteristics of the ground, such as urban and suburban areas or open terrain with some obstructions or flat areas like open water.  There are 4 risk categories.  Category I is low risk to humans, such as agricultural facilities. Category III includes, for example, buildings for public assembly, colleges and universities, and water treatment facilities.  Category IV includes essential facilities like hospitals and police stations.  Category II is everything else—most roofs are Category II. A building shall be classified as enclosed, open or partially enclosed. The enclosure classification is used to determine the internal pressure coefficients used to calculate design roof pressures...(Continued)

How much wind can a metal roof withstand? We can determine this from the metal roof installation down to the residential roof design. In doing so, roofing contractors can adjust and make modifications and improvements that make sure your roof is ready to handle any kind of windstorm at any time.

Remember to work with reliable and capable professionals. If you have yet to find a reliable roofer with experience in London ON, you can count on Cub Roofing's experienced and exceptionally-trained professionals to help you. Contact us today to learn more about what we can do for you!

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352 Talbot St
London, ON N6A 2R6
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