It is a misconception to believe that hurricane anchor is placed in the foundation. On the contrary, hurricane anchors shall be installed in the roof truss chords and connected to a column or stiff wall.
Any wind force creates an uplift force in a building. These uplift forces are normally harmless and do not need to be taken into account since the weight of the structure will sufficiently counteract with the uplift force an nivellate it. However, it is a different story with a hurricane force wind. These exrtremely high wind forces create tremendously high uplift forces and will blow the roof away when the roof truss system is not properly anchored. The uplift reaction forces are transferred to the foundation via the hurricane anchors, whereas the foundation anchors also need to be designed to safely absorb these forces (it is normal engineering practice to oversize the foundation to utilize its weight to a factor of 1.2 x the total uplift force).
Prefabworld Bali International applies vertical steel rods, tighlty installed onto the truss chords as to deal wth the calculated uplift forces.
So far all of our units built in a cyclone area have safely sustained a hurricane force wind:
|♦||In September 2004 one of our buildings withstood hurricane Ivan that struck the Cayman islands|
|♦||In November 2009 a 2-storey unit designed and prefabricated by us lost only some roof tiles when the island of Sta. Lucia in the Caribbean was hit by hurricane Thomas|
|♦||Eary November 2013 the Phillipines were hard hit by typhoon Haiyan. Our A-2 model sustained the 315 km/h (196 Mph) storm|