Raised flooring

A raised floor (also raised flooring) is a type of floor used in office buildings (such as IT data centers) with a high requirement for servicing to carry cables, wiring, electrical supply, and sometimes air conditioning or chilled water pipes. Additional structural support and lighting are often provided when a floor is raised enough for a person to crawl or even walk beneath
Design

This type of floor consists of a gridded metal framework or understructure of adjustable-height legs (called "pedestals") that provide support for individual floor panels, which are usually 2×2 feet or 60×60 cm in size. The height of the legs/pedestals is dictated by the volume of cables and other services provided beneath, but typically arranged for a clearance of at least six inches or 15 cm.

The panels are normally made of steel-clad particleboard or a steel panel with a cementitious internal core. There are a variety of flooring finishes to suit the application such as carpets, high-pressure laminates, marble, stone, and antistatic finishes for use in computer rooms and laboratories.

Many modern computer and equipment rooms employ an underfloor cooling system to ensure even cooling of the room with minimal wasted energy. Cooled air is pumped under the floor and dispersed upward into the room through regularly spaced diffuser tiles or through ducts directed into specific equipment. Automatic fire protection shutoffs may be required for under-floor ventilation, and additional suppression systems may be installed in case of under-floor fires.

Because the flooring tiles are rarely removed once equipment has been installed, the space below them is seldom cleaned, and fluff and other debris settles, making working on cabling underneath the flooring a dirty job. Smoke detectors under the raised floor can be triggered by workers disturbing the dust, resulting in false alarms.
Panel-lifter
To remove panels, a tool with a suction cup on the end (referred to as a "floor puller", "tile lifter", or "suction lifter") is used. A hook-and-loop lifter may be used on carpeted panels.
Structural problems

Structural problems are a serious threat to both equipment and personnel on a raised floor. Problems such as rocking panels and gaps between panels can cause permanent damage to a floor system, personnel injuries, and damage to equipment. Regular underfloor inspections for structural integrity of a raised floor system should be carried out.

Various trades servicing in and around an access floor can disturb the grid and pedestal system creating structural hazards. The load rating of an access floor is established when all components are properly installed. Floors perform to specifications only when they are structurally sound. Supporting understructure should be inspected at least once a year.
Cooling load implications
The installation of a raised floor system can change the thermal behaviour of the building by reducing the interaction between the heat gains and the thermally massive concrete slab.[1] The raised floor serves as a separation between the room and the slab. Energy simulations of an office building located in San Francisco showed that the mere presence of the raised floor affects the zone cooling load profile and tends to increase the peak cooling load. When carpeting is present the negative impact of the raised floor on zone peak cooling load may be reduced