 An empty, well built snow structure, 16 or more hours old, in weather below −12 °C (10 °F) may be strong enough to support a group of adults standing on top of it.All snow shelters eventually collapse or melt.Quinzhees can collapse from poor snow conditions, warm weather, blowing rain, construction problems (hitting a supporting wall), failure to let the snow sinter long enough, or from people climbing on them.