Floor systems in mid and high rise office buildings are engineered to provide fire protection between floors. Typically, the floor system consists of a concrete floor poured over a metal pan that has been installed to the building framework. This floor assembly is rated for fire resistance and provides an important part of the fire-life safety features of these buildings.
Service of electrical and voice and data low voltage wiring is often routed to the workstation from the electrical service panel and voice and data equipment room through the ceiling plenum of the floor below and up through a hole in the floor that has been cored for this purpose. This cored hole breaches the fire control aspects of the engineered floor system; the hardware that is used in mounting and terminating the wiring is designed to maintain the fire control properties of the floor system.
For many years, tenants of high-rise office buildings were not required to remove their electrical service and low voltage wiring so installed when they vacated the premises. Over time, however, and with the increased use of desktop computing, the amount of low voltage wiring left behind reached an unsustainable volume. Building management recognized this issue about 20 years ago and began requiring vacating tenants to remove all low voltage wiring installed during their tenancy.
The removal of this wiring and its attendant mounting hardware created a breech in the fire control properties of the floor system. In effect, each abandoned core became a chimney, or pathway for fire to move from floor to floor. Building owners now require that these abandoned cores be filled by the vacating (or remodeling) tenant.
The traditional way to properly restore the fire control properties of the floor system is to fabricate and install a metal patch to the underside of the cored hole, then fill the hole with concrete from above. In many cases, access to the underside of the cored hole is not possible or econmoncially practical. In most situations such a repair is time consuming and expensive.
As a result of the complexity and cost of performing proper repairs, haphazard repairs are performed from the top side of the abandoned core. Rags, fiberglass insulation, paper, and other material were stuffed in the hole, and the hole filled with some readily available concrete-like material such as Fix-It-All or Drywall mud. This type of repair obviously did not restore the fire protection properties of the original floor system and, in fact, created a hazard caused by the repair shrinking and falling through to the floor below. In addition, many repairs did not provide a solid flush floor, which created more problems.