Raised Floor

What are raised floor and how do they work?

A raised floor is an elevated structural floor which is placed above a concrete slab leaving an open space between the two structures. The open space acts as a hidden passage or an empty space for the placement of mechanical and electrical equipment. Raised floors are often pre-­designed features in modern office buildings and in command centres, IT data centres and computer rooms, where there is a need to route mechanical services, wiring, cables and electrical supplies.

The use of access flooring allows for the creation of more flexible and sustainable work spaces. If the space is large enough for a person to either walk or crawl through, then additional structural support and lighting should be installed. Access floor usage will continue to grow in popularity as more companies design buildings to meet LEED (Leadership in Energy & Environmental Design) specifications.

The raised floor takes the form of a gridded metal frame of adjustable height called pedestals that provide support for movable floor panels. The height of such flooring ranges from 2 inches to more than 4 feet, depending on the types of services (the volume of cables and other required equipment) that can be accommodated beneath.

The floor panels are made from steel­ clad particleboards or a steel panel with an internal core. The floor panels usually have a variety of finishes that include carpet tiles, marble, stone, antistatic and high­ pressure laminates for use in laboratories and computer rooms. For office areas, hallways, museums, casinos and lobbies, the panels are left bare and sealed or stained and sealed.

Most modern computer and equipment rooms use an underfloor air distribution system to ensure an even cooling of the room to minimise energy usage. This underfloor ventilation system works by allowing conditioned air under the floor to flow upwards into the room through evenly spaced diffuser tiles, blowers or ducts.

In addition, to prevent underfloor fires, fire protection shutoffs are installed. However, once the equipment has been installed, the flooring tiles are seldom removed and a lot of dust and fluff can gather below. Sometimes smoke detectors under the raised floors may be triggered when the dust particles are disturbed, resulting in false fire alarms.

Building costs as well as operational costs can be lessened when at the outset of the building project, underfloor air system is predesigned into the building structure. The equipment required for underfloor air like blowers and air handlers are smaller in size and are energy ­savers. Buildings that are designed to integrate modular electrical, modular walls and access flooring, allows the space to be easily and quickly reconfigured to allow for the routing of electrical and other services.

Regular inspections for structural integrity of a raised floor are required to help identify and mitigate structural problems. Rocking panels and gaps between panels can cause significant damage to equipment and injury to people. Equipment and floor damage will happen when flooring does not meet load demands. Also the thermal environment of the building can change with the installation of a raised floor system.

Raised Floor Application

Telecommunications data centres have special raised floor requirements. The types of raised floors include :

stringered raised floor­ with a vertical arrangement of steel pedestal assemblies uniformly spaced and mechanically fastened to the concrete floor;

stringer-less raised floor­ with an arrangement of pedestals that gives the required height for routing cables and support to each corner of the floor panels;

structural platforms­ a network of steel angles and channels that are placed together to form a platform for supporting equipment;

truss assemblies­ where the floor panels are resting on the truss network which is supported by attachment points on the subfloor. The truss has high lateral strength and transfers lateral loads to the subfloor with less strain.