Demolition services include the destruction and cleanup of buildings, sitework, roadwork and other installations. To safely demolish a structure, demolition services must carefully map each site element. First, they review the architectural plans for information about structural supports and connections. Next, a crew tours the area and examines the support structure in detail. Based on this analysis, demolition experts then select which equipment and explosives (if any) to use. In some cases, blasting crews develop three-dimensional (3D) computer models to ensure that structures collapse in a predictable manner. In the case of a building on a city block, for example, demolition services may also secure steel cables to support columns.
Demolition services perform activities such as vibration prediction, vibration monitoring, noise monitoring, structural inspections, and project photography. Vibration prediction and impact calculation studies may use vibration data collected from the demolition of similar structures. Vibration monitoring brings seismographs into the field to study liabilities posed by surrounding structures. Noise monitoring equipment is also used to take various types of field measurements, and may comply with standards such as ANSI S1.4. Structural inspections provide clients with a record of pre-existing conditions in case of subsequent litigation or potential damage claims. Demolition services may also use project photography to provide customers, insurance carriers, and government agencies with a visual record of a project’s progress.
Demolition services use a variety of demolition methods and demolition equipment. Choices include implosion, long-reach arm, crane and ball, and selective dismantlement. Implosion is a method of controlled demolition in which explosives are strategically placed and timed so that a structure collapses upon itself. Building implosion does not rely upon the difference between internal and external pressure, but rather weakens critical supports so that the building can no longer withstand gravity. Demolition services that use long-arm cranes with breaker jaws, cranes and balls, and other excavating equipment are also available. Typically, demolition cranes consist of a winder, wire ropes or chains and sheaves, and wrecking ball.
Explosive demolition services are licensed to use explosives to demolish bridges, buildings, smokestacks, apartment high-rises, and vacant industrial sites. Like other demolition contractors, they comply with requirements from the U.S. Occupational Safety and Health Administration (OSHA). Demolition services that meet safety requirements from organizations such as the National Demolition Association (NDA) are also available.