One of a roof’s biggest enemies is wind. Strong winds can seriously damage a flat roof and undermine its durability. It is important to be aware of the potential problems caused by wind damage, and to check for them after a wind storm.
The most common problem is from wind uplift. When wind blows across a flat roof, it reduces air pressure above the building and the higher air pressure within the building pushes upward against the roof. The stronger the wind, the stronger the uplift.
If designed specifically for the building height and location and installed properly, a commercial roofing system should withstand “normal” wind conditions for that setting (hurricanes and tornadoes being exceptions). However, after any significant wind event, it’s a good idea to check the condition of the roof, especially along the perimeter, as that’s where troubles typically start. When membrane is pulled up from the deck due to uplift, water can get underneath and cause problems. Plus, even a small gap in the membrane perimeter can give wind more roof material to “take hold of,” and hasten the failure of the roof.
Even relatively “low” wind speeds – say, 40 miles per hour (not uncommon for taller buildings and those in coastal areas) – can pry loose fascia and other details from the roof edge, as well as get under membrane seams and detach flashing from other areas.
Wind “scouring” or “scrubbing” is another potential issue caused by consistent, strong winds. This occurs when roof gravel, or ballast (used on some systems), is blown around or even off the roof, creating an uneven distribution of the stone on the rooftop and exposing the membrane beneath. Wind scouring might not create immediate problems, but it can shorten the roof’s life span over time if it is not addressed. After a wind event, make sure that the ballast is still spread evenly across the roof.
The effect of wind on a roof should never be overlooked, especially as your roof gets older. Consistently strong winds will make it more susceptible to wind damage. It’s important to inspect your roof regularly – especially after wind events – to ensure that it maintains its integrity in all areas.