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