Wind Uplift Concerns for Property Owners and Construction Managers

Roof damage from wind uplift.

When installed and maintained correctly, most roofs perform as expected. At the same time, most are not designed to withstand Toronto’s extremely windy, stormy weather. Sometimes, roofing systems can be damaged even by moderate wind speeds. The maximum wind gusts in Toronto in December 2023 and January and February 2024 were in the top end of the previously observed  events. In short, wind is a significant factor of potential property damage.

Wind Uplift Concerns for Property Owners and Construction Managers

One of the most important considerations for developers and roofing professionals is how well a new or  replacement roof will hold up against high winds—especially in GTA and other areas with severe storms. Being a responsible builder, property owner, and property manager requires understanding what wind uplift is, related risks to property, and how to prevent damage in the future.

Damaged roof from wind uplift.

What is Wind Uplift?

In significant storms, wind blows parallel to the surface of a flat roof. When air infiltrates the roof structure, it is directed upward, creating pressure under the roof and reducing air pressure above it. This differential in pressure can create a dynamic lift that causes the roof material or membrane to separate from the building. Wind lift is an especially high risk in areas where wind-driven rain is common—such as Toronto.

What are the Consequences of Wind Uplift?

When wind lift occurs, wrinkles and bubbles can form beneath the surface, leading to problems including:

  • Cracking, moisture, and leaks can deteriorate underlying materials.
  • A roof that is partially or completely blown off leaves the underlying structure exposed to the elements.  
  • Fasteners, adhesives, and other roofing components can fail if not designed with adequate wind resistance. Improper installation can add to these problems.
  • In the worst case scenario, the roof deck could potentially detach from the supporting structure, especially if the roof deck has open joints.

Roof damage from wind uplift.

What Factors Contribute to Wind Uplift?

Engineers and developers are responsible for following all local building codes and designing the roof assembly as recommended by manufacturers to prevent wind uplift. The first step is understanding the complex factors that contribute to wind lift.

Wind uplift factors include:

  • Wind speed, wind direction, and wind duration
  • Location, terrain, and exposure
  • Roof material type, quality, condition, and age
  • The shape, geometry, orientation, and height of the roof
  • Topographic futures 

Roof damage from wind uplift.

The developer’s team must weigh these factors to gauge the wind loads placed on the structure and determine the appropriate type of roof and installation method for the project.

Which Flat Roofing Systems are Most Wind-Resistant?

Bitumen Roofing Systems

Bitumen roofing is known for effectively mitigating the effects of severe winds, hurricanes, and tornados. The roof deck is securely attached to the roofing material, which may be strengthened with screws or nails, enabling it to maintain the roof’s integrity when facing strong winds.   

Modified Bitumen

Thanks to its high tensile strength, mod-bit systems are highly resistant to roof punctures, tears, and water damage that can occur during wind events—even withstanding winds of up to 175 km/h. and are highly resistant to water damage. Wind resistance can be enhanced by using the hot, torch-down installation method.  

Metal

Metal roofs, which are highly durable,  can withstand winds of up to 225 km/h. They have long-been popular in hurricane-prone areas.  

Single-Ply Roofing Systems

When properly installed, single-ply roofs tend to hold up fairly well in high-wind situations when installed and maintained according to manufacturer guidelines. The problem is that there are many loose laid ballasted roof assemblies that are susceptible to wind blow offs especially when the ballast moves around over time.  

The concern with single-ply roofing systems is that wind will catch under the membrane like a tarp and rip it, with roof edges and corners being the most vulnerable areas. Whether using mechanical fasteners or adhesives, roofers and engineers must pay special attention to choosing and correctly implementing the fastening system, especially at parapet walls and upturns.

Is There a Standard Test or Rating for Wind Uplift?

There is no universal system in place for establishing wind uplift ratings. Four of the most common testing standards in use today are:

  • UL 1897: Safety testing for uplift of roof covering systems
  • UL 580: Standard testing method for uplift resistance of roof assemblies
  • ASTM 1592: Standard testing method for structural performance of sheet metal roof and siding systems
  • FM 4471: Class 1 approval standard for roofing panels.

Do Canada and Toronto Have Roofing Requirements for Wind Uplift?    

  • FM Approvals is the most commonly specified wind uplift criteria in the Greater Toronto area. FM (Factory Mutual) Approvals provides third-party product testing and certification with I-60 and I-90 classifications. This refers to how many pounds per square foot (psf) of wind uplift tested pressure the roof system can withstand.

Other wind uplift criteria that may be used include:

Regardless of which rating systems you use, there is no testing standard that is absolutely foolproof. You never know what Mother Nature will throw at you, especially as climate change advances. At the same time, codes and guidelines help ensure that builders do their best to construct roofs that will minimize the risk of damage and roof failure from wind uplift.

How Can You Minimize the Risk of Wind Uplift Problems?

As a property owner or developer, you are responsible for minimizing the risk of uplift and its damaging aftermath. Following the recommendations below will provide your roof with greater wind-resistance:

  • Properly install roof flashings and check for loose or dislodged metal copings after a wind event.
  • Build the roof according to or exceeding the code, which may have changed since the roof’s original installation.
  • Always use proper type and quantity of fasteners or roofing adhesive(s)
  • Pay  special attention to specified system details around parapet walls and roof upturns.
  • Keep up with routine maintenance. Call a professional roofer and set up a plan for your roof to be inspected twice a year and after significant weather events.

Keep Your Property Safe from Wind Uplift Damage

There are three important steps to avoiding damage from wind uplift.

  1. Work with a reputable, expert engineer and roofing contractor to determine which type of roofing system will best protect your commercial or industrial building. 
  2. Hire a contractor with experience correctly installing roofs for maximum wind-resistance. 
  3. Work with a reputable, expert roofer who can perform routine maintenance, twice-annual inspections, and an inspection after significant wind events.

Protect Your Roof by Partnering with a Top Toronto’s Roofing Contractor

Prevent unwanted property damage by hiring roofers with the experience to secure your property with a wind-resistant roof that stands up to whatever Toronto’s weather serves up. Since 1956, Elite Roofing has proven its expertise, craftsmanship, and integrity to commercial property owners throughout GTA. We understand the impact of wind in our area. Trust us to select the most wind-resistant roof for your project, install it with superior workmanship, and be there when you need us with 24/7 emergency service. Contact us today and get the Elite Advantage.