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Critical Defect

Referenced initially in Australian Standard AS 1851:2012 a critical defect is a form of defect or fault that renders a system or item of equipment inoperative or is likely to render the system or item of equipment inoperative placing a one or more people at significant risk (death or injury) or an asset (or building) at significant risk (loss or damage) of from fire or related emergency.

Australian Standard AS 1851 introduced the terms non-conformance, non-critical defect and critical defect in the 2012 edition of the Standard. The definition was accompanied by a flowchart (Figure 1.5.6 - Routine Service Activity Failure) to illustrate the difference between each of these terms.

AS1851 2012 Critical Defect Non Conformance Flowchart - Table 1.5.6 Routine Service Activity Failure


In Queensland, the term "critical defect" is defined in the Building Fire Safety Regulation 2008 to provide additional clarity  as follows;


Meaning of critical defect

A defect in a prescribed fire safety installation for a building is a "critical defect" if—

(a) the defect is likely to render the installation inoperable; and

(b) the defect is reasonably likely to have a significant adverse impact on the safety of occupants of part or all of the building if a fire or hazardous materials emergency happens.

Examples of critical defects—

  • a defect making a fire detection and alarm system inoperable
  • a defect in a pump making the fire hydrants for a building inoperable

Example of a defect that is not a critical defect—
a defect that makes inoperable only 1 of several standard fire extinguishers in a part of a building


In preparing this definition, we have drawn from various sources including Legislation, Codes, Standards and industry information, research and knowledge.  Like the english language, these definitions may subtly change from time to time. As such these definitions are provided solely on the basis that users will be responsible for making their own assessment of the definition and and are advised to verify all relevant representations, statements and information.