Position paper: Risks associated with induced collapse on residential properties

Issue

Induced collapse involves the systematic/sequential removal of key structural members and the application of a force to result in the controlled collapse of all or part of a building or structure.

However, the method being used in residential demolition has resulted in uncontrolled collapse of all or part of a building.

Background

This demolition method has many risks. It can result in significant injury or fatality, and cause damage to nearby properties.

Inspectors have observed the following potential problems with induced collapse on residential properties:

• Close proximity to other properties.
• Lack of planning or expert advice on which structural members to remove to pre-weaken the building.
• Workers re-entering the demolition footprint to remove further structural members when the induced collapse was unsuccessful.
• Wire ropes, slings, and chains that haven’t been maintained properly.
• Use of plant and machinery to demolish a structure on residential streets, without using traffic control.
• Persons inside the exclusion zone with potential to be struck by wire ropes, slings, or chains in the event of a failure of these items.
• Lack of exclusion zones during induced collapse.

PCBU obligations under the WHS Regulation 2017

The Work Health and Safety (WHS) Regulation 2017 places several obligations on persons conducting a business or undertaking (PCBUs) in relation to managing risks to health and safety.

• Clause 35 – Managing risks to health and safety. A duty holder, in managing risks to health and safety, must:
  • eliminate risks to health and safety so far as is reasonably practicable, and
  • if it is not reasonably practicable to eliminate risks to health and safety, minimise those risks so far as is reasonably practicable.
• The Work Health and Safety Act 2011 (Section 18) defines 'reasonably practicable'. Our position is that it is 'reasonably practicable' to undertake the demolition of residential houses sequentially to prevent the need for workers to re-enter the demolition footprint if an induced collapse was uncontrolled.

Position

SafeWork NSW recommends that you:

• undertake demolition work sequentially to prevent unexpected collapse
• seek expert advice from a competent person, such as an appropriately experienced structural engineer, prior to considering an induced collapse method on any property
• only consider induced collapse methods on detached, isolated structures on reasonably level sites
• ensure there is available sufficient space into which collapsing material can fall without the structure or debris able to impact on nearby properties
• check there is sufficient space for plant, equipment, and personnel to be removed to a safe distance prior to collapse
• maintain wire ropes, slings, and chains in good condition, have them checked by a competent person, and ensure they are compliant with relevant Australian Standards.

Guidance

Code of Practice - Demolition Work 2019 (PDF, 668.8 KB)
AS 2601-2001 The Demolition of Structures