Strong Winds and Your Building
I came to the office on Monday after a beautiful weekend to see that a part of the roof of our office building at the university had been blown off by a strong wind. It wasn’t only the roof that was affected but the ceilings and the facade’s curtain walls in the direction of the wind.
I moved round to observe the effect of this wind on neighboring buildings, trees, sign boards and telecom masts and saw that the wind was so strong that it uprooted a few trees, dug out pad foundations of sign boards, removed several roofing sheets of other buildings and knocked a few telecom mast over.
I will normally not be bothered by this but for the fact that our building is occupied by the faculty that carters for future built environment professionals … young curious minds, who may want to know what happened to their beloved faculty building and how they can design against such.
I for one, as an architect was curious to know what made our building more susceptible to wind damage than other buildings and what could be done in the future to forestall or limit these damages.
I also observed that most of the old buildings ie those built in the 70s, 80s and 90s within the university sustained minimal or no damage when compared to those built in the millennium …is there something the older architects know that the younger ones do not?
I mentally documented a few observations I will like to share and believe we can learn a few lesson from this incident to forestall or reduce any occurrence of wind damage on your building, especially those sited in windy areas:
- I saw that buildings with reinforced concrete (RC) roof slabs, parapet walls with peripheral roof gutters and up stand/ inverted RC beams ‘guarding’ roofing sheets withstood the winds better than roofs with exposed timber eaves projection and roof mounted on concrete facial (the concrete cornice- like eaves projection). Which shows that building whose roof were either completely concrete, concealed or shielded from direct wind experienced lesser damage.
- Asbestos roofing sheets and other sheets with thicker gauges withstood the winds better than lighter gauges of long span aluminium sheets. Which suggests that the density of any roofing sheets may have a role to play in a roof’s ability to withstand excessive wind load … also here I observed that certain roof forms/designs were more prone to wind damage than others.
- Ceilings that weren’t properly anchored nor their boards pinned down firmly such as the popular suspended 600mm X 600mm grided ceiling couldn’t withstand the wind at all. Architects can learn from this so that when specifying this ceiling type would ensure at supervision they insist that these ceilings are well anchored and pinned down properly to help reduce the effect of wind load on them. This is because my thinking is that once the wind gains access into the building and beats the ceilings the next thing is to blow out the roofing sheets and damage the roof. Alternatively we can recommend other ceiling types if we are designing in areas prone to strong winds.
- Buildings with wind breakers such as trees etc experienced less damage compared to the ones with insufficient trees of which my office building is one… therefore architects need to re-emphasize and promote these once again, because besides trees beautifying the environment they also protect our buildings from severe wind storms.
- Also poor roofing practice and substandard timber sizing for roof trusses can cause roofs to fail under strong wind. Example of these practice are timber tie beams that weren’t sufficiently anchored and pinned down on concrete facials which creates a weak points in the truss link from where the wind will commence its damage. Also using a lesser timber sizing or mixing up the sizes of timbers used as roof members can compromise the strength of the roof.
- Buildings that had some of its windows panes opened or broken by the wind sustained more roof damage than buildings whose windows where more intact. I observed that windows with larger glass spans shattered and therefore resisted minimal wind load when compared with window with smaller glass spans. Which suggest that by having smaller glass partitions formed by mullions on windows we can strengthen the window against wind, therefore reducing the amount of wind coming into the building to cause damage …but where we intend to have excessive glass span we may consider using laminated or structural glass.
Please feel free to add your suggestions on other precautions we can take to forestall wind damages in buildings.