Rubble found at a structural collapse could weigh from less than 1 kg to several tonnes.

Surface hazards could include:

* False floors and differences in elevation
* Sharp surfaces
* Holes
* Rubble
* Nails and reinforcing bars, steel conduit and copper piping

Climate – Snow and ice makes traversing a rubble pile almost impossible. Snow will hide voids and levels, conceal sharp objects, reduce visibility and possibly impose additional weight on the structure

Surfaces – Surfaces will be uneven and unstable in debris piles, creating slippery and dangerous conditions. Using a lowered body height and the rubble crawl will help you to safely traverse the rubble pile.

Sharp and jagged objects – Care must be taken to avoid sharp and jagged objects in the rubble pile of a collapse environment. Beware of cantilever objects – they are not capable of supporting a body weight.

Pooling of water – Pools of water may be from broken water mains, sewage lines or local flooding. A pool of water can appear shallow although it could be deep enough to cause a drowning. Pools of water also hold major risks of infection, as there will often be sewage leakage.

Dust and Wind – After a collapse has occurred, large plumes of dust can choke the surrounding air for long periods of time. Walls may look sound but with gusting winds may collapse without warning. Winds may also affect communications between working teams.

Noise and vibrations – Excessive noise on site can sometimes be unavoidable. There is a set of signals to call for silence if it is required. Vibration from equipment could contribute to secondary collapse.