Why Are Thatched Roofs Blown Off in a Storm?

Wind

• The strong winds that accompany a storm place great pressure and suction on a building. Thatched roofs in good condition can withstand these forces as well as most other roofs. However, thatched roofs in less-than-ideal conditions may not be able to withstand the wind load. When such wind damage occurs, it is often concentrated at the top or the edges of the roof. Areas that have been damaged by weeds and animals are likely to be affected.

Shape

• The shape of a thatched roof plays a big role in determining its resistance to storms. A good thatched roof has the height, gable shape and orientation that allow it to have proper air flow underneath the roof. With sufficient ventilation, a thatched roof is able to resist the wind forces during a storm. Thatched roofs that are blown off during a storm may not have the correct shape and ventilation system.

Layers

• A thatched roof has to be attached directly to the rafters to provide maximum protection during a storm. Aside from reeds, the roof contains brass screws, steel wires and steel rods. This installation method provides strength for the roof to withstand heavy wind. If the thatcher fails to correctly layer the thatch roof, the structure may not have sufficient integrity to survive a storm.

Age

• A well-maintained thatch roof can last for decades. However, the thatch layers naturally become thinner over time. Because of this, the roof requires regular maintenance every eight to 10 years, during which the thatcher replaces the roof ridge. Other parts of the thatch roof may also require repairs every few years. Without proper maintenance, the roof may deteriorate to a point where it does not have the structural strength to stay on top of a building during a storm.