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Control measure
Cordon control: Unstable structures

Control measure knowledge

The hazard area for an unstable structure that may undergo partial or structural collapse needs to take into account:

  • Construction materials
  • The height and type of the structure
  • Severe weather conditions, such as flooding, heavy snow or high winds
  • The potential for damage to surrounding structures and infrastructure

In the UK, a portal or rigid frame construction is designed for inward collapse – in a fully developed fire a basic single storey structure may be expected to collapse within 30 minutes. Portal frame structures are generally designed so that they collapse within their own footprint.

Cordons may need to consider the potential collapse of scaffolding and tower cranes. On a construction site they could collapse outside the existing hoarding or site boundary. For further information see the hazard: Scaffolding.

Glass (glazing) or other flat panels falling from height may travel (plane) significant distances from a structure, particularly in windy conditions.

Specialist advice may be required from local authority building control teams, structural engineers or urban search and rescue tactical advisers.  

Strategic actions

Fire and rescue services should:
  • Make arrangements with other agencies to establish the type and level of response they can provide if specialist advice is required

  • Ensure personnel are aware of the specialist advice available

Tactical actions

Incident commanders should:
  • Evaluate and monitor the potential footprint of collapse and debris

  • Consider seeking specialist advice when defining the hazard area for a potential collapse