Introduction
The meaning of the word ‘demolish’ is deliberate and controlled collapse of a structure. During the late 70’s Fred Dibnah took over as the most widely known steeplejack in The UK when his work on demolishing large chimneys without the need for explosives was shown on Tv. Fred was an interesting personality and became renowned as an authority on fixing tall chimneys, so when it came to taking them down he knew the best way to make it happen. He normally would chop an niche at the base of the chimney, and place wooden props to hold the structure. By means of meticulously setting the props, the chimney would collapse in the right place when the wood was set alight and burned away. Once he was very nearly crushed because he miscalculated somewhat, demonstrating just how risky demolition work really is.
The particular term to demolish only came to exist in 1570, and was used from then on to mean the deliberate taking down or destroying of a building or structure. Although in reality the job of demolition, in some form or other, has been occurring for millenia. Structures have been destroyed either by natural disruptions of the Earth’s crust or during battles or attacks on communities for as long as there have been buildings. The surviving ruins would be removed and rebuilt or used by other properties in the area and must be early examples of recycling.
Preserving the Past - Preparing the Future.
To conserve Britain’s tradition of farming the acreage between the built up parts of the villages and towns is shielded from expansion of urban sprawl. This acreage is known as Green Belt and it is preserved for farming that is fundamental to the continuing economy of the country. By conserving the Green Belt, urban areas are being squeezed to supply housing, so developers need to be much more resourceful to find appropriate sites.
Britain is a nation with an incredibly dense population per square mile. The quantity of land available for construction is small in comparison to other countries. Consequently there’s always a high need for space on which to build. Taking down aged and unused structures and replacing them with new is an excellent method to attempt to counter this general shortage.
Land which may be disused industrial and commercial sites, but could be polluted with hazardous waste or pollution, are classified as Brownfield sites. Once the land has been cleaned up they’re potentially valuable for redevelopment. Both Glasgow and South Wales developed gardens from disused commercial sites and installed Shopping centres to draw in holidaymakers and visitors and generate income.
Greyfield sites are totally different to Brownfield sites in that they don’t possess the environmental issues of harmful waste materials. The term greyfield arises from the large areas of asphalt that had once been car parks of commercial urban buildings. Their worth is in the indisputable fact that the commercial infrastructure like highways, electricity, water supply, sewerage, and gas is already in position. These urban areas which become under-utilised or abandoned and are important because they require a small amount of remedial work to be exploited. Cities including Leeds and Manchester have had a massive programme of changing the existing warehouses or industrial facilities into flats, retail establishments and cafes, keeping the original shell and refurbishing the interior into desirable accommodation.
The Demolition Process
Any experienced and professional Birmingham demolition contractor should be able to make an assessment of the following basic items.
The construction type and actual physical size of the building.
What items have re-use value?
What will the cleared site’s re-use be for?
Where are the waste material by-products going to be disposed?
What precautions need to be made with regards electricity, water, sewerage and gas mains.
Hydraulic excavators and bulldozers can be used to undermine the walls at the bottom, so the structure will topple; at the same time controlling the manner and course of the fall. Questions of safety are very important, and clean-up plans are usually looked at when determining the way the structure will be demolished.
Old fashioned Demolition
In the old days the traditional way of demolishing a property was extremely crude. After the services were disconnected, the men and machinery would expect to go in and just knock down the walls. Then the whole structure would collapse and the ensuing debris would be piled onto trucks and be dumped in land fill sites. Concrete footings were split up by pneumatic tools and the site could be cleared of waste ready for the new work to commence. Then again nowadays demolition businesses are at the mercy of stringent planning, safety and monitoring regulations and so are hugely controlled by the local council. How a building is constructed will mean that one part is dependent on the other for solidity and sturdiness. For example the rooftop of a building isn’t fastened down save for fixing roof tiles with nails to prevent them sliding. The rooftop stays in place using its own weight because the beams are laid on the top of the walls rather than being fastened into them like they were in the past for much older houses. The cross beams and purlins then tie the entire thing together to secure the frame of the roofing. To this slats are laid to provide a frame for laying on the tiles or slates. Some other sections of a building are interdependent so in terms of demolition these factors are considered in the sequence of deconstruction. In this way, like Fred Dibnah you need to be an expert in construction to understand how to do the deconstruction.
Deconstruction and Recycling
The new approach to demolishing properties is known as deconstruction - an environmentally friendly approach. Landfill sites are in limited supply therefore the aim when demolishing a property is to diminish the volume of waste remaining.
Small constructions such as 2 or 3 storey buildings can be disassembled quite easily. The work may be a slow task of dismantling by hand - brick by brick - or beam by beam but by proceeding with care expensive resources are preserved for re-use. The value of deconstruction is that 90% or more of waste material is prevented from going straight into landfill sites and reclaimed materials can be re-used and recycled for upcoming structures. The farmer opposite my family home sold his barns inside the farm yard for construction; when the builder demolished the barns he cleaned up the bricks and reused them to make the walls around the farmhouse thereby keeping the character of the farm.
Newer specialist techniques and equipment enables demolition contractors to effectively segregate waste groups on or off-site. Building resources are recycled and re-used if practical in the new building making significant reductions in project costs in addition to being good for the environment.
Concrete can now be easily cracked using a large guillotine.
Through the use of the new Birmingham crushing plant machinery the demolished building bricks and stone can be recycled into 6f2 recycled materials for use on new buildings. Crushed material from the demolition can be used as a sub-base for the new building foundations or used on other sites where construction is underway.
Copper pipes, lead, roof tiles or slates, floor tiles, wiring and doors, and wooden panelling are valued objects which can be saved for recycling to be re-used. Many specialist businesses offer reclaimed old or antique building supplies in a lot of towns and cities.
Tall Structures
Tower blocks and chimneys are the type of tall buildings that may need to be demolished. The demolition of tall buildings requires skilled tactics. The tallest structure to be demolished lawfully was in 1967/8 for the Singer Building in New York. The fall of the World Trade Centre after the 9/11 attack in late 2001 demonstrates the horrible devastation that is caused if the demolition is unchecked and haphazard.
In the demolishing of tall buildings and larger structures a wrecking ball on a crane can be used, but is hardly ever used because the swinging ball is relatively uncontrollable. The closeness of other property is a deciding issue that inhibits the usage of explosives to implode a tall building. So ‘High Reach’ demolition excavators are used wherever other approaches aren’t suitable to demolish the highest section of a tall building. Once it is down to a manageable height demolition can continue in the usual way. The various methods of demolishing tall buildings are by implosion using explosives, controlled collapse and piecemeal. To control the dust produced in demolition, water hoses and spray equipment are sometimes used and then it is called a wet demolition.
Explosions
The use of explosives in demolition is incredibly specialist work and getting it wrong would be disastrous. If for instance there is atmospheric pressure from low cloud above the implosion site, the shockwave may spread outwards instead of upwards resulting in the wave of energy and sound to break glass windows. If the implosion is not prepared correctly the risk might be destruction of surrounding buildings where flying debris could cause injuries to spectators.
For many individuals when they consider demolition they might have in mind the use of explosives in the spectacular collapse of a tall building. This method is actually called implosion using explosives. Implosion is vital for dense towns as it brings down a tall building so the surrounding environment is damaged as little as possible. The collapse takes only mere seconds for the building to drop into its footprint.
Because of the hazards of working with explosives they will only be used when other methods are too costly or impractical. Where there is a partial collapse of the building and there are still primed explosives that failed to go off, workers will be in great danger because the remaining structure is very unstable. On top of that the demolition has to continue to secure the safety of the site.
Health and Safety
The work of demolition is a much more technical and complicated process than most people would appreciate. The work is highly dangerous and requires experienced and skilled operators to carry out the work. It is vital that personnel working in the market are thoroughly trained. Health and safety awareness is necessary in demolition services so it is advisable for operatives to have gained certificates of Competence in Demolition to guarantee safety for both workers and public alike. All demolition jobs are regulated by Construction, Design and Management Regulations.
Before the demolition of a building in Nottingham project starts make sure your demolition contractor has used a similar process to gain demolition planning approval.
Sequence of Demolition
An incorrect sequence of dismantling can lead to premature collapse of a building since the stability of any structure is reliant on the interdependence of its component parts. Consider a house of cards and what are the results if one of many supporting cards is taken away.
There is a strict sequence of events before any demolition will take place. Councils all over the country have their particular specific list for planning approval in their area, but a typical order would be as follows:-
Provision of data
Information has to be provided about the construction of the structure to be demolished. Details of its previous use and also the appropriate demolition methods to be employed, including disposal of hazardous substances, need to be submitted by the demolition company.
Survey of Demolition
A comprehensive survey of the site to identify any structural problems, in addition to risks related to hazardous or flammable substances, should be discussed in detail with the authorities. (E.g. A disused garage where petrol was stored is often a potential fire hazard so preventative measures will have to be taken).
Preferred and Safe Method of Work
A reputable demolition company should be able to select the right way of disposal showing the outline dismantling process. Planning is essential for assiduous monitoring. The authorities will require a detailed statement of the safety procedures to used, and all parties involved have to agree the techniques before any demolition will take place.
Preparation and Planning
Issues such as asbestos abatement, rodent baiting, dealing with hazardous substances, disconnecting utilities, and making safe any electric, gas or other services must be shown in the planning stage. There is plenty of preparation to be done before even starting work on demolishing the structure itself.
Protection of the Public
Safety can’t be compromised so where there are heavily populated areas around the demolition site the protection of the public is paramount. Any health risks will need to be assessed and temporary services arranged, and individuals disturbed will have to be informed.
Conclusion
The aim in demolition is always to eliminate an unwanted structure as safely and quickly as possible also in our modern environment attempts are made to recycle or re-use the majority of the old material. This may not be a brand new idea although the word itself is relatively modern. On the borders between England and Scotland after the Romans left, a significant part of Hadrian’s Wall was hauled away and use was made of the beautifully dressed stone to construct the new buildings in the towns and villages nearby and several remain standing today.
Demolition work by its nature is a very dangerous business and demolishing any building is a complex and skilled process. Next time you observe demolition work occurring on a building offer a thought to the people who work in a dangerous situation daily and how much is involved in the meticulous planning, regulations compliance, care and skill that goes on to carrying out the project to clear the path for our future.
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