A flat roof can be made of different materials, including ethylene propylene diene monomer (EPDM), a built-up roofing (BUR), modified bitumen, metal and single ply. To prevent wind and rain from lifting the edges of a flat roof, fascia and metal flashing are installed.
Flat roofs are often preferred over sloped or pitched roofs when the application is for a tall building. A sloped or pitched roof will add to the height of the building, use up more material and also be more dangerous during installation and roof repair because the roof is not level. Buildings often have outdoor AC units installed on the flat roof, which is not practical if the roof is sloped. Some buildings also have other features on their flat roof, including gardens and smoking areas, also impossible with a pitched roof. One more reason to use a flat roof on a tall building is that it has less wind resistance.
Wind Uplift
However, even if the roof is flat, it will still have to contend with the elements, including wind. Wind uplift is one of the most destructive forces that all roofs face, including flat roofs. Wind uplift happens when wind finds its way underneath the roofing materials and pulls them up. This is why there are often wrinkles or bubbles in a flat roof. This means the material is no longer as securely attached as it once was.
Some roofs are sturdy enough to withstand mild to moderate winds, but they can still be damaged by strong winds, such as those brought on by hurricanes and tornadoes. Other, less-sturdy roofs can be damaged even by moderate winds, particularly if the building is quite tall.
Other Factors That Add to Damage
Because of the wind’s power to lift a flat roof, it can cause rain and snow to get underneath the material. This worsens the damage caused by wind uplift as the materials under the roofing membrane are now exposed to moisture. This can lead to rot, corrosion, staining, mold and mildew growth, and termite infestation. Debris can also be blown under the membrane.
Preventing Wind Uplift
Roofing contractors understand the effects of strong winds on the systems they install. They have several ways to minimize the possibility of wind uplift. For example, they have to make sure the metal edge flashing around the flat roof is fastened as securely as possible. They also need to ensure the fascia is strong enough to resist wind uplift to prevent it from destroying the edge flashing.
It’s important for building owners or property managers to have the fascia and the flashing inspected regularly to make sure they are fastened correctly, particularly after an extreme weather event. If problems are observed, they should contact their roofing contractor as soon as possible.
Wind Scouring
Wind uplift is not the only destructive force that commercial roofs have to face. Wind scouring might even be more prevalent. The wind might not be able to cause uplift when the roof is securely fastened, but the surface on top of the roof might still be vulnerable to wind scouring.
Wind scouring happens when a gust of wind is strong enough to blow off the granules from the roof or to deplete the gravel on a BUR system. The danger of wind scouring is that it isn’t quite as quickly noticeable as wind uplift damage because it can happen slowly. Unless you look closely or hire a professional for roof repair and maintenance, the damage can go unnoticed until more damage makes it too obvious to ignore.
Factors That Determine Wind Damage Severity
Wind speed - The strength and speed of the gusts of wind that hit your roof can determine the severity of the damage. The higher the wind speed, the more damage it can cause. However, it would be a mistake to think only very high wind speeds are detrimental to the condition of your roofing system. Even wind speeds of 40 to 50 miles per hour (mph) can already cause enough lift to loosen or destroy edge flashing or fascia.
Wind duration - It’s not just the speed of the wind that can damage a roof; it’s also how long it blows. Even low wind speeds can be highly damaging if they blow for hours against a roofing system.
Wind direction - The direction of the wind also determines the severity of the damage to your roofing system. If the wind is blowing against the direction of a roofing material, chances are very high that - given enough time - the wind will succeed in lifting the material.
Condition of the roof - Roofing contractors often emphasize the importance of regular inspections and maintenance as these can help prevent expensive repairs in the long term and also help lengthen the lifespan of the roof overall. If a roof is in poor condition, it doesn’t take a lot of wind to create uplift and eventually cause damage. A poorly maintained roof has a much lower chance of survival than one that receives proper and regular upkeep when exposed to the same extreme weather conditions.
Quality of the materials - Sturdy roofing materials have a better chance of surviving against strong winds than cheaper materials.
Quality of installation - It’s important to hire professionals during a roof replacement or new roof installation project. The quality of the workmanship has a direct impact on how the roof performs against the elements, including and especially the wind.
Weather conditions and climate - The climate in the area where the building is located can also determine the scope of damage relative to wind speed. Some areas are windier than others, and some have an extremely hot climate while others have freezing temperatures, all of which can affect the condition of the roofing system and its resistance to wind. Extreme weather events also play a huge role in how long a roof can last.
Wind damage and the factors that determine how a roof survives against strong winds are something to take seriously. For more advice on this and for roofing requirements, including roof replacement, get in touch with A1 Quality Roofing, Inc. Call us today at (951) 877-4406, or reach out to us through our contact page.