Specification 4 Design of buildings in cyclonic areas

(1) Where a residential building of Class 2, 3, 9a or 9c, in Region C as defined by AS/NZS 1170.2, is designed to be used by the Aged or Infirm it shall incorporate a “strengthened area” for use as shelter during cyclonic conditions and must comply with the following criteria:

1. The floor area of the “strengthened area” is to be calculated at the rate of 1.2 m² per person normally accommodated within the building.
2. The design wind pressure for the overall “strengthened area” is for an Importance Level 3 building.
3. The minimum standard of debris protection to walls, floors and ceilings (or roof) bounding the "strengthened area" shall be that which resists (without complete penetration) the impact loading specified in AS/NZS 1170.2, using a regional wind speed associated with an Importance Level 3 building.
4. All doors, windows, vents and the like in walls bounding the “strengthened area” are to be protected against windborne debris with permanently installed screens in accordance with (c).
5. Consideration must be given to the selection of materials and fittings to ensure doors, windows and vents can withstand the required design wind pressures.
6. All doors serving as required entries/exits to a “strengthened area” are to be inward opening with locking devices suitably noted for use in a cyclone emergency.

(2) The term “strengthened area” is defined as the strengthening of an area to increase its potential to facilitate debris protection.