David Allan Coe beautifully quoted “It is not the beauty of a building you should look at, it is the construction of the foundation that will stand the test of time”. Who said only a human has to change with time? What about the building that has been constructed years ago? Demolition is done when some vital facilities need to be repaired - like underground plumber lines, electric utility lines, sewage lines, etc. During expansion, the existing building may require additional space, sometimes for this purpose partial demolition is done but under highly controlled circumstances. Generally, demolition is done by using an excavator or other heavy machines.