Often times before new building construction begins the demolition of an existing structure must take place. This is not as simple as knocking it over, breaking into pieces, and carting away. Reclamation and recycling of resources used in the existing structure, handling of hazardous materials, and environmental impact all are key considerations. Typically correct demolition process is best done by a separate company with equipment and expertise in the field.
The demolition process begins with a thorough assessment of the structure. Ideally this will consist not only of a physical walkthrough inspection but whenever possible a review of blueprints and plans from modifications throughout the life of the building. This enables the demolition team to make accurate estimates of time, manpower, and equipment needed. Testing is also often done in this phase – to check for hazardous materials such as lead based used in the past, asbestos, or hazardous insulation of years past as examples.
Looking at the original construction method will offer insight into the safest method to begin demolition. Particularly on taller structures a controlled demolition is essential for worker safety and to prevent widespread contamination in the form of airborne fibres and particulates.
If hazardous materials such as asbestos are found to be present they must be removed in an environmentally controlled setting prior to other work commencing. Depending on previous usage, testing is sometimes done to test porous material and the ground for absorption of liquid or airborne contaminants used in the building previously. Such absorption can make materials that are typically relatively benign need special handling.
Reclamation and recycling of valuable materials such as copper wiring and pipes, aluminum fixtures, and steel support is always considered. This recycling process can offset many of the costs of a typical demolition process and typically is taken as part of the service by the demolition company. The order of removal is best determined by the engineers. Sometimes most or all of the wiring as an example is done prior to structural demolition, but on occasion it is extracted as the building is torn apart.
Specialized equipment is used to break concrete from steal structure supports. It is sometimes done by setting up an onsite plant or the Demolition Services may transport it to an offsite or permanent recycling plant. This often is determined by space availability around the structure being demolished.
Most demolitions do not stop at ground level. The extraction of contaminated soil and ground below the structure and parking surfaces is typically required as well. When properly done a demolition project ends with maximum recycled materials, a safe and clean site to begin new construction, and minimal environmental impact on surrounding areas.
Submitted by Brian Colton