Design pathways for suspended ceilings
While suspended ceilings are specifically excluded from NZS 4219:2009, AS/NZS 2785:2000 provides similar specific and non-specific design pathways. Unlike NZS 4219:2009, the pathway that the designer should select depends on the seismic demand determined by NZS 1170.5:2004 (not NZS 4203:1992). This takes into account the location and importance of the building, component categories and the requirements of ceiling being designed.
This information and AS/NZS 2785:2000 are then used to determine whether the suspended ceiling requires a specific design or if a non-specific design will be sufficient.
Non-specific design for suspended ceilings
Non-specific design guidance, which is usually provided by the suspended ceiling manufacturer, may be used to achieve a compliant design. This is provided the guidance has previously been confirmed to comply with the requirements of the Building Code by a suitability qualified New Zealand-based engineer or seismic specialist.
Non-specific design guides typically provide a prescriptive solution to calculate the seismic restraint requirements for the type of ceiling being considered.
Specific design for suspended ceilings
More complex projects will require a specific design, which must be conducted by a experienced and suitably qualified seismic specialist or ceiling designer. A suspended ceiling may require a specific design for a number of reasons, including:
- complexity of the ceiling arrangement
- size of the ceiling
- building importance level
- depth of the ceiling
- adjacent and connected services and building components
- expected operational life of the ceiling.
Irrespective of the design pathway chosen, all suspended ceiling designs must be able to accommodate the seismic demand calculated using NZS 1170.5:2004. The accommodation may be by way of restraint or by allowing for unimpeded movement.