Which of the following is NOT a common type of void encountered with building collapse?

The identification of voids in the context of building collapses plays a crucial role in search and rescue operations as well as in understanding potential hazards. Among the various types of voids that can occur when a structure fails, the spiral void is not commonly recognized or documented.

Pancake voids occur when floors collapse directly onto one another, creating a flat, layered effect. Lean-to voids form when one part of a structure remains standing while another section falls, resulting in an angled void. V-shaped voids occur when two walls collapse inwardly, creating a void that resembles a "V" shape and can be especially dangerous because it may trap victims in enclosed areas.

In contrast, the spiral void is not typically described in discussions of building collapses or void types. This absence from established literature or operational guides suggests that it does not have the same prevalence or importance in tactical considerations during incidents involving structural failures. Therefore, identifying it as not a common type of void aligns with current knowledge and practice in firefighting and emergency response.