Feature article

Ensuring buildings stand up to heavy snow

Following the 12 June 2006 Canterbury snowstorms, the Department of Building and Housing engaged NIWA to undertake a study to examine snow loading in New Zealand. This was prompted by the collapse of several buildings from the heavy snowfall, and the concurrent review of the proposed new building standard AS/NZ 1170.

The NIWA report showed that there were insufficient snow loading data for a robust review of the proposed building standards, and recommended a systematic data collection campaign following future severe low-elevation snowstorms. This data collection campaign would permit accurate snow loading calculations for the AS/NZ building standard..

NIWA has now developed two methods for the collection of ground snow load data. One method addresses exceptional low-elevation snowfall events (e.g., the Canterbury snowstorms), and the other method is for general snow loading at higher elevations. The data collected using these methods will set the benchmarks for snow loading requirements for buildings at low altitudes (<900 m) in the eastern and southern regions of the South Island, where most low-altitude snow risk occurs, and will ensure that standards for buildings at higher elevations are based on systematic observations.

The overall purpose of this work is to produce a simple, repeatable methodology which is efficient and accurate for ground snow load surveying, and to establish uniform sampling procedures. Increasing our database of ground snow loading will ensure that the building standards are in line with observations, and improve our understanding of the probability of observed snow depths in various locations.

For more information, contact Dr Jordy Hendrikx: (j.hendrikx@niwa.co.nz)