After the recent, significant damage to buildings inflicted by Storm Arwen at the end of November 2021, we decided to share some information about the potential disruption caused by wind uplift.
What is wind uplift?
In its simplest form, wind uplift is a term used to describe the movement of air above an object, whether that’s a building, a tree, or a hill.
Once the wind comes into contact with a vertical surface, such as a wall – regardless of the direction it’s approaching from – its current is accelerated upwards, creating an area of negative pressure which is known as a “void”.
Due to the speed at which the wind is travelling, wind uplift can cause considerable damage. Not only does it carry harmful debris, but if the wind is strong enough, the negative pressure can begin to lift and pry away the roof’s membrane, initial localized damage can then allow the wind to get under the roof system posing a risk of more significant damage. The debris can cause a potential safety risk to people in the area and there can be substantial repair bills related to this damage.
To add some perspective, this is the same type of force harnessed to propel aeroplanes into the air.
Where does it pose the biggest challenge to flat roofs?
In a recent LinkedIn poll, we asked our followers to identify which location was most likely to suffer the effects of wind uplift on a flat roof – buildings in coastal locations, buildings above 15-metres high, buildings in isolated settings, or all of the above. The answer, of course, was all of the above – well done to the 85% of people who answered correctly!
A building’s location and exposure are key to determining the effect of wind uplift. Northern England, Scotland and Northern Ireland typically have higher than average wind speeds, compared to the South of England.
Wind speed is also higher in exposed areas, such as along the coast and in open, rural, or hilly areas. Buildings above 15-meters with no surrounding shelter also have a higher chance of suffering the ill effects of wind uplift.
It should also be mentioned that flat roofs which have not been installed correctly have a higher chance of suffering greater levels of damage, too. That’s why site surveys which identify vulnerable sites are vital.
Wind uplift calculation
When undertaking a roofing project, wind uplift calculations must be considered to ensure the correct level of protection is applied.
This calculation will determine the wind uplift pressures acting on the roof. The level of pressure a roof could have to cope with will vary depending on numerous factors such as location, height, size, and type. This data allows accurate assessments on the suitability, type and amount of roofing fixings needed for this site.
From free condition reports to site surveys, we’ve got it covered. For all roofing products, including Elastaseal Z – our innovative zero-odour liquid-applied waterproofing system – we offer a free wind uplift calculation to ensure you’re getting the best level of protection for your money. So, get in touch and book your free site survey with our experts today.