The requirement to demolish or refurbish a building occurs for a variety of reasons. It is essential that the demolition process is adhered to.
Every building has a lifespan which is known as its ‘design life. An architect will design a building with perhaps a life span of 80 -100 years. When it has reached the end of its life span, it might become dangerous for habitation or to the adjacent buildings around it.
Other reasons are that new ones replace old structures. The structure has lost its stability, or it may have structural damage.
Demolition – means destruction, breaking down or removal. The Demolition of a building is the process of dismantling a structure after its life span or serviceability by pre-planning and controlled demolition methods.
A demolition plan illustrates the different process involved, and they are:
All the workforce will have a site induction and toolbox talk to discuss methods and environment
Fire and emergency plans are prepared and included within the health and safety induction.
As a matter, of course, measures are put in place to reduce and monitor, Dust, noise and vibration.
All the workforce wear full PPE. Occupational health checks are carried regularly for all demolition workers.
There are two types of Demolition employed for buildings and structures
Non-explosive or controlled demolition
Implosion is the Demolition of a building by explosives. With the removal of the foundations, the structure will collapse. This method is used mainly for large factories and power stations. Most Demolition in Towns and Cities is carried out by conventional means.
This method involves the main supports of a building, including column's, beams and slab fixed with explosives. Once the explosives detonate, the building will collapse.
Depending on how the structure falls, there are two types of implosion:
The implosion makes the building fall like a tree sideways and is the most common method of implosion. Where the building has sufficient area around it available besides the building, this type of Demolition is preferred.
If there is free space available on the left side of the building the explosives are placed on the lower level of the building on the left-hand-side columns. As the explosives detonate, the columns bursts and the building will fall towards the left-hand side. Cables are tied to the building and control the direction of the fall.
When there is limited space around the building, this type of Demolition selected. Explosives are placed into the floor below the middle part of the building.
These explosives are substantial as the explosion must demolish the building at once. It is a series of blasts, one followed by another. Then the building falls towards the first blasted part.
When the charges detonate, the upper part of building implodes and falls onto the lower building. The heavy load and force the lower part of the building also collapses and falls on its footprint.