C5 Evidence Report Phase 2

Final Report commissioned by the Ministry of Business, Innovation and Employment (MBIE) and prepared by Engineering New Zealand, has been released.

In 2019 MBIE commissioned this report from Engineering New Zealand, in which the revised C5 Section (Yellow Chapter), has been used alongside the original C5 version (Red Book), within the 2017 Engineering Assessment Guidelines. The aim of this research was to further test the impact of the Yellow Chapter on building assessments, when compared with the Red Book involving comparative assessment of the precast concrete floor systems.

Phase Two of the C5 Evidence Project assessed a further 12 buildings using the Red Book and the Yellow Chapter with a specific focus on precast concrete floor systems. While there were some notable differences in the assessments of some individual buildings, the evidence also revealed little difference, on average, in overall %NBS between Red Book and Yellow Chapter assessments.

Phase Two also found that practitioners reported the Yellow Chapter provided better insight into building components requiring strengthening and is more straightforward to use.

Next steps

No changes are proposed to the Engineering Assessment Guidelines at this stage. MBIE will consider the findings of the C5 evidence report to determine what steps, if any, may be taken.

Engineers must continue to use only the legislated July 2017 Engineering Assessment Guidelines (Red Book) to carry out detailed engineering assessments to identify earthquake prone buildings.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: