Q: What is demolition?

A:Demolition is the tearing down of a building or other structures or parts of them; it’s the opposite of construction. It differs from deconstruction, which is the taking down of a building in order to preserve materials or parts that can be reused.

Q: How is demolition of a building or other structure accomplished?

A: For a house or other smaller structure of fewer than three stories, the process is simple. The structure is pulled down manually or mechanically using large hydraulic equipment such as elevated work platforms, cranes, excavators, or bulldozers. Large structures may require the use of a wrecking ball, a heavy weight on a cable that is swung by a crane into the side of the structure. Wrecking balls are especially good for knocking down masonry, but can be less efficient than other methods.

Some new methods use rotational hydraulic shears and silenced rock breakers attached to excavators to cut or break through wood, steel, and concrete. Shears are also commonly used if using flame cutting in a situation may be dangerous. Explosives are a third method of taking down a structure. This is called implosion and is generally used on large buildings, tall chimneys, smokestacks, and sometimes smaller structures. The collapse of the building through explosives is very fast, taking only a few seconds, and can be extremely accurate when done by a professional. This ensures safety when doing it to tall structures in dense urban areas. Because of the danger involved in implosion, however, it is generally only used as a last resort when other methods are not feasible.