Lightweight building construction is a common present day construction type.


Buildings constructed using lightweight materials that are not sufficiently protected by sprinklers or effective non-combustible structural protection systems may collapse much sooner than expected. Warning signs that are commonly present in fires that involve legacy construction are not present in these situations.

Unprotected lightweight trusses, fastening systems, wooden “I” beams, lightweight steel frame construction and other engineered construction components are quickly compromised when exposed to heat and flame.

Firefighter fatalities and injuries have occurred as the result of rapid structural failure.

Actions for employers

Employers should:

  • identify buildings with lightweight construction in their response area

Employers must:

  • make firefighters and incident commanders aware of the hazards of lightweight construction
  • make firefighters aware of any known locations of buildings with lightweight construction in their response area

Safety considerations

Incident commanders should:

  • consider the type of construction, the presence of protective sprinkler systems, and to what extent the structure may have been damaged by the fire, before initiating firefighting strategy
  • consider employing defensive fire attack strategies within buildings that contain unprotected lightweight construction and where no threat to human life exists
  • continually evaluate the risks during operations in buildings that contain unprotected lightweight construction
  • assume that unprotected lightweight construction is present, if unable to determine the type of construction in a building

Consider the following in procedures:

  • the unique hazards of buildings built with unprotected lightweight construction, emphasizing firefighter safety and the likelihood of an early unpredictable collapse
  • use of a thermal imaging camera to help locate fires
    • recognize that the camera cannot be relied upon to assess the strength or safety of the floor
    • firefighters should be trained on the use of thermal imaging cameras, including limitations and difficulties in detecting fire burning below floor systems
  • use extreme caution when operating on or under an unprotected lightweight truss roof or floor
  • evacuate as soon as it is determined that the unprotected trusses are exposed to fire
  • develop emergency warning procedures for evacuating a building in danger of collapse, and practice regularly

Applicable regulations and acts


  • Occupational Health and Safety Act
    • clause 25(2)(a) for providing information and instruction to a worker
    • clause 25(2)(d) for making workers aware of hazards
    • clause 25(2)(h) for taking every precaution reasonable in the circumstances to protect workers