What is a raised access floor system?
A raised access floor comprises of load bearing floor panels laid in a horizontal grid supported by adjustable vertical pedestals to provide an under floor space for the housing and distribution of services.
The floor panels are readily removable to allow quick access to the under floor services.
What are the key components of a raised access floor system?
The key components of a raised access flooring system can be defined as follows:
This is the horizontal load bearing component of a raised floor. It is normally 24"x 24" square (industry standard module size) but can be 24" metric square.
These sizes are nominal sizes and clarification should be sought from the manufacturer as to their stated panel size and tolerances. These floor panels will be supplied as either bare finished to accept a carpet tile finish on site or, with a factory bonded finish.
This is the complete vertical, adjustable supporting structure to the raised floor panels. The pedestals are normally bonded to the sub floor using a epoxy resin based adhesive with mechanical fixings also provided if required. The pedestal assembly provides vertical adjustment of 1½" to allow the raised floor to be installed flat and level despite undulations in the sub floor. The pedestal head provides panel location and also when required a means of fixing the panel to the pedestal head.
This is a horizontal component that connects pedestals together. It connects to the pedestal head and is used to provide additional lateral support at greater floor height and/or increase the structural
performance of the raised floor system.
Where is a raised access floor used?
Raised access flooring is used today in a wide range of situations where there is a significant level of building services. Examples include:
- Financial and Insurance offices where there is a need for a significant level of computer/telecom equipment.
- National and Local Government offices, again there is a need for a significant level of computer/telecom equipment.
- General administration buildings across the complete range of industries where the use of computer/telecom equipment is widespread.
- Call Centers. Office environments set up to handle large-scale customer enquires thereby requiring significant levels of computer/telecom equipment.
- Data processing centers. Large scale computer rooms set up for the processing of electronic data e.g. customer information, financial information.
- Telecom switch centers. Old mechanical telephone exchanges now replaced by electronic switch facilities. Also new mobile technology requires new electronic switch facilities.
- Distribution centers. These facilities distribute a vast range of fast moving consumer goods with order processing and such activities handled in a modern office environment.
- Educational facilities. Raised flooring used in specific learning areas in schools, universities etc. Also used in library and major archive areas.
- Retail facilities such as major department stores increasingly using raised floors surfaced with special finishes.
- Industries requiring clean room facilities such as electronic and pharmaceutical.
- Light industrial and specialist industries where flexibility and the use of under floor services would be advantageous.
Why use a raised access floor?
A raised access floor is used to provide a means of creating a void below floor level which is capable of ensuring building services are available at their required destination. These services will typically
include the following:
- electrical power
- environmental control/air conditioning
- fire detection and suppression
- water and drainage.
The use of a raised access floor will allow quick and easy access to these services for maintenance reasons. Also in today's modern office environment Churn is a major issue. That is the number of times that the office layout has to be modified to cater for changing requirements brought about by new technology, new personnel or new tenants to a building.
What are the benefits of using a raised access floor?
Raised access floors are used extensively to provide the following benefits:
- Quick and easy access to the ever increasing volume of power, data and telecom services found within a modern building.
- The underfloor void or cavity depth is often used as a large duct for HVAC systems.
- In speculative buildings premises need to be adaptable for the needs of incoming occupiers.
- Once occupied offices need to cater for office Churn and lend themselves to new office organizations and layouts with the redirection of services that implies.
- Accessibility is a major consideration. People want easy access to the services for maintenance, rerouting or upgrading with as little disruption as possible to the work process.
What is the construction of a floor panel?
There are various basic floor panel constructions that are outlined below along with various attributes of each type.
Steel encased woodcore. This panel construction comprises of a high density particle board core that is encased by galvanized steel laminated to the particle board by a structural polyurethane or epoxy resin adhesive. This construction type is capable of providing high strength and good fire and acoustic performance. By varying the thickness of the steel sheet and the strength of the chipboard core a wide range of structural performance is available.
Steel/cementitious panels. Here a structural steel shell comprising of a flat steel top and a profiled steel base are welded together to form a hollow shell. This shell is then filled with a foamed cement based core to give a panel that gives good structural performance in conjunction with excellent fire performance. In certain cases the hollow unfilled steel shell will provide a floor panel that gives suitable structural performance although its acoustic performance is limited.
What are stringers and why use them?
Stringers are introduced for various reasons each with their own specific design.
Snap on stringers. These snap onto the pedestal head and are used to provide additional lateral support to the raised floor. They are normally introduced at floor heights of 24" and above or for use with floor panels complete with factory bonded finishes. Snap on stringers are normally designed to increase the structural performance of the raised floor.
Bolt on stringers. These are screwed into the pedestal head and are designed as structural components and as such increase the structural performance of the raised floor system. They will also provide increased lateral stability.
Air plenum stringers. These stringers are designed only as a means of providing an air seal to the panel joints through the use of a gasket strip. They do not provide any increase to the lateral stability or structural performance of the floor.
Perimeter stringers. These provide additional support to cut panels around the perimeters if required by the project specification
What type of surface finishes are available?
The following range of floor finishes is available:
Here the floor panel will not be finished with a surface covering. The surface of the panel will normally be the epoxy powder coated steel top sheet. This bare finished raised floor will normally be covered on site by the application of loose lay carpet tiles.
Factory applied finishes
The following finishes can be supplied factory bonded to the appropriate floor panel:
- Anti static vinyl
- Static conductive vinyl
- High pressure laminate
- Wood in various forms
- Stone, ceramic tiles.
- Other finishes may be available after evaluation.
What range of finished floor heights (FFH) is available?
Using standard pedestals finished floor heights from 3" to 48" are achievable. Bespoke solutions for lower and higher options are available.
As a general rule above a finished floor height of 24" stringers will be introduced to provide additional lateral stability.
What is the exact definition of finished floor height?
The finished floor height (FFH) is defined as "The nominal vertical dimension from the specified sub floor level to the specified finished floor level".
How to avoid problems associated with raised access floors?
As the raised access floor performs a critical function within the working office environment faults with the system can cause problems from simple annoyance through to major disruption. Many faults are rectifiable to a varying degree, however it is essential to consider the following key factors to prevent such occurrences.
- Use of inappropriate products and/or solutions
- Use of inappropriate class or grade of raised access floor
- Poor quality products and/or installation
- Raised access floor not lifted and replaced in accordance with manufacturer's instructions
- Lack of appropriate maintenance.
- Movement, rocking and squeaking of floor panels
- Difficulty in removing and replacing panels
- The floor may require modification in order to perform satisfactorily
- Areas of floor or the complete floor may require replacement
- Possible floor collapse with likely damage and injury.
In order to avoid the problems outlined it is important that the raised access floor be correctly specified at the outset. This specification should include not only the product requirements but also the installation requirements. Once installed the raised floor must be maintained correctly in line with the manufacturer's instructions.