Load resistance

Bracing enables the roof, wall and floor framework to resist horizontal forces (racking forces) applied to the building. These forces include:

  • live loads - people, furniture etc
  • dead loads - structural elements
  • wind loads.
Diagram showing construction loads (people, materials) acting downwards on a house, including the dead load of the structure itself and the live loads of people, furniture etc.Diagram showing loads on a house caused by wind (acting inwards) and suction (acting outwards) on the external walls, suction (uplift) acting on the roof, and internal pressure acting inwards and outwards from inside the house.

Wind classifications

The wind classification needs to be known when designing a bracing system.

Winds are classified according to:

  • building height
  • geographical region
  • terrain category
  • shielding classification
  • topographical classification.

The following are the classifications for non-cyclonic regions:

  • N1 - W28N for 100 km/h gust
  • N2 - W33N for 120 km/h gust
  • N3 - W41N for 150 km/h gust
  • N4 - W50N for 180 km/h gust.