5. DEMOLITION METHODS
When jack hammering concrete floors, sufficient reinforcing steel should be left in position as protection against collapse or to prevent persons falling through the floor.
MANUAL DEMOLITION OF FRAMEWORKS Before any framework is demolished or removed, all reasonably practicable precautions should be taken to prevent the rest of the building collapsing as a result.
A competent person( for example, a structural engineer) should undertake an assessment to determine the necessary supports required when cutting members. Members should not be cut unless they are supported safely and effectively. Measures should be taken to prevent sudden spring, twist, collapse or other movement of the framework when it is cut, released or removed.
Any framework which is not demolished should be strong enough to remain safely in position, or should be guyed or otherwise supported to ensure that it will be stable in any adverse weather conditions.
Framework members should be lowered in a controlled manner. Tag lines should be used on loads where necessary to control the load.
5.2 Mechanical demolition
Mechanical demolition involves the use of powered mobile plant, such as excavators, cranes, loaders and bulldozers. There may be a mix of hand and mechanical demolition methods applied.
All powered mobile plant used for demolition work must be fitted with a suitable combination of operator protective devices.
Operator protective structures should be designed to the appropriate standard that eliminates or minimises the risk, so far as is reasonably practicable, of operator injury due to:
• roll over and consequent cabin impact damage
• objects falling on or over the cabin
• objects penetrating the cabin •hazardous noise.
Demolition should be planned to be systematic and sequential. That is, a structure should generally be demolished in the reverse order to which it was constructed.
WORKING ON SUSPENDED FLOORS Suspended floors and their supporting members should not be loaded by workers, plant, falling or accumulated debris / materials to the extent that there is excessive deflection, permanent deformation or danger of collapse. If water is used, the increased weight of the watered debris should be taken into account.
If powered mobile plant will be operated on a suspended floor, the demolition contractor should ensure that a competent person( for example, a structural engineer) verifies and documents:
• the type, size, weight and usage of any specified plant
• that the floor is capable of sustaining the static and live loads of the plant( including attachments) and demolished materials, without excessive deformation or collapse, either:
28 CODE OF PRACTICE | DEMOLITION WORK