Demolition

Demolition of the Old Myer Building, Perth (Australia).

Demolition of a hospital in the city of Seville.

Demolition or tear down is the opposite of construction: the destruction of buildings and other structures. The tallest building demolished was the 47-story Singer Building in New York City, which was built in 1908 and torn down between 1967 and 1968 to be replaced by One Liberty Plaza.

For most buildings, such as houses, that are only two or three stories high, demolition is a simpler process. The building is demolished either manually or mechanically using numerous hydraulic equipment: elevated work platforms, cranes, excavators and bulldozers.

Larger buildings may require the use of a wrecking ball, a heavy weight suspended from a cable that is swung by a crane onto the building's façade. Wrecking balls are especially effective against masonry, but are more difficult to control and often less efficient than other methods. Newer methods may use rotary hydraulic shears and quiet stone crushers in conjunction with excavators to cut or break through wood, steel and concrete. The use of shears is especially common where cutting with a torch would be dangerous.

Building implosion

Tall buildings and chimneys and increasingly some smaller structures can be destroyed by building implosion using explosives. Imploding a building is very fast—the collapse itself only takes seconds—and an expert can ensure that the building falls within its own perimeter, so as not to damage nearby structures. This is essential for tall structures in densely built-up areas. The biggest danger is flying debris that can kill bystanders if improperly prepared. Even more dangerous is the partial failure of an implosion attempt. When a building does not completely collapse, the structure can be unstable, leaning at a dangerous angle, and filled with unexploded but still intact explosives, making it difficult and unsafe for workers to approach.

It takes several weeks to prepare a building for an implosion. All valuables, such as copper wiring, are removed from the building. Some materials must be removed, such as glass that can form deadly projectiles and insulation that can spread over a wide area. Some selected columns are perforated and some explosive with high breaking power of the Rionel or Goma 2 type is placed in their holes. The supports and load-bearing walls can be eliminated with detonating cord. The goal is to use the least amount of explosive possible; only a few plants are loaded with explosives. Blast areas are covered with wide plastic and fencing to absorb flying debris. Much longer than actual demolition is site cleanup, as the debris is loaded onto trucks and transported to another location. The destruction of large buildings has become increasingly common as the massive housing projects of the 1960s and 1970s collapsed around the world. At 450 square feet and 204,000 square feet, the J.L. Hudson Department Store and Addition is the tallest steel frame building and the largest structure ever to implode.

Controlled implosion is the method the general public normally thinks of when talking about demolition. It is a demolition system that is often applied to high-rise, free-standing or complex structures such as bridges, cooling towers, chimneys, high-rise antennas or silos, especially when other methods are impractical or too expensive. It does not entail greater risks than another demolition system, and sometimes even has many advantages, as long as it is carried out by technicians with extensive experience in this field. It has a significantly lower accident rate than other demolition systems and a significantly smaller field of application.

Demolition materials

Usually the buildings that were affected by accidents (earthquakes, fires, natural catastrophes), or that are about to be demolished, since a new one is built on that land, or on the structure that remains from the demolition, they leave in charge from the demolition companies the openings, iron, bars, floors, stairs, roofs and other materials, which are carefully extracted to be able to reuse them in other constructions. These materials are generally very valuable, since they were used in very old houses, they are unique, and usually they no longer have competition, they are not built anymore. Wrought iron, pine trees, carob, parquet floors, masonry, openings, columns, countertops, stairs, etc. They can be found at demolition sales outlets.

Types of demolition

Mechanical demolitions

Development with heavy machinery: loader and excavator on tracks, removal of material with dump truck. They are used to carry out demolitions on a large scale and in places of risk where the personnel cannot be present. These machines are operated by highly qualified personnel, respecting the corresponding safety and hygiene regulations.

Traditional demolitions

We work with specialized labor, using traditional techniques, in order to preserve walls, party walls and structures, in this case heavy machinery is not used.

Demolitions in accidents

Works on accidents, dangers of landslides and building emergencies.

Waste management

In Spain, the production and management of waste from demolition work is regulated in order to promote, in this order, its prevention, reuse, recycling and other forms of recovery, ensuring that waste destined for disposal operations receive adequate treatment, and contribute to a sustainable development of this activity. For such purposes, the drafting of a Construction-Demolition Waste Management Plan (RCD) is mandatory.

Associations

In Spain, the sector is represented by the Spanish Association of Demolition Employers (aeded).

Disarmaments

Recovery of parabolic roofs (sheds) and dismantling of parts that are no longer useful, due to age, accident or because their useful life has expired and are discarded to be scraped (cut, disassembled and recycled).