What is demolition?

Both demolition and deconstruction involve the pulling down of a building or structure and are the reverse of the construction process. Whilst the two processes are similar in effect deconstruction preserves various elements of the structure, such as wood, and bricks, for reuse for another building or structure.

The process involves Rotational hydraulic shears and rock-beakers attached to specialist excavators are also used to cut or break through wood, cut steel and crush concrete which reduces the structure to a rubble which is either treated as waste or, in some cases, used as hard core for other construction projects.

Deconstruction is a relatively new approach that seeks to minimise the quantity of waste that is sent to landfill sites. The process involves the careful removal of materials and segregating them either for reuse or recycling.

A well-designed deconstruction project can result in less than 20% of the structure and its contents being transported to landfill fees and cost saving in refused materials can make it a cost-effective process. There are two forms of demolition:

1. Piecemeal- where the demolition is conducted using hand and mechanical tools such as pneumatic drills, cranes and demolition balls, hydraulic pusher arms or heavy duty grabs; and 
2. Deliberate controlled collapse – where explosives are used to demolish the structure. This technique should only be used by trained, specialist competent persons. Pre-weakening of the structure, by the removal of several load-bearing elements and their replacement with temporary props, normally precedes the deliberate collapse. This is the most economic form of demolition but it is the most hazardous and everyone must be at a safe significant distance at the time of the collapse.