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Knowledge Base
Raised Access Flooring Performance Grades
Understanding Light, Medium, Heavy & Extra Heavy Raised Access Floors
Raised access floors are designed to accommodate very different levels of loading – from standard office environments through to data centres and specialist facilities containing extremely heavy equipment.
The PSA MOB PF2 PS/SPU Performance Specification provides four recognised performance grades for raised access flooring:
LIGHT → MEDIUM → HEAVY → EXTRA HEAVY
These grades provide architects, specifiers, manufacturers and contractors with a consistent method of defining the structural performance required from a raised access flooring system.
What Does the Performance Grade Apply To?
It is important to understand that Light, Medium, Heavy and Extra Heavy are performance grades of the complete raised access flooring system – not grades of pedestal adhesive.
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The performance of a raised access floor depends upon the interaction of its components, including:
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• Floor panels
• Pedestals
• Stringers, where applicable
• Pedestal fixing
• Installation quality
• Subfloor condition
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A high-performance panel installed onto an inadequately designed or poorly installed supporting structure does not automatically create a high-performance raised access floor.
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The Four Performance Grades
LIGHT
Primarily intended for general office accommodation without heavy equipment. Light Grade provides the lowest of the four PSA performance classifications but remains suitable for many conventional office environments.
MEDIUM
Typically specified for general office accommodation containing heavier equipment, educational accommodation, data preparation areas and public areas. Medium Grade provides increased concentrated and uniformly distributed load capacity compared with Light Grade.
HEAVY
Designed for more demanding applications such as computer rooms, communications facilities, telephone exchanges, control rooms and other areas containing substantial equipment loads. Heavy Grade significantly increases the concentrated-load capability of the floor system.
EXTRA HEAVY
Intended for particularly demanding applications including computer rooms and data centres containing heavy equipment and other specialist installations. Although the headline concentrated and uniformly distributed loads are similar to Heavy Grade, Extra Heavy Grade includes an additional four-point loading requirement representing particularly demanding equipment loads.
Performance Is Hierarchical
The PSA performance grades are arranged hierarchically.
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This means that a raised access floor system achieving a particular grade must also satisfy the performance requirements of the grades beneath it.
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EXTRA HEAVY
↑
HEAVY
↑
MEDIUM
↑
LIGHT
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The correct grade should therefore be selected according to the actual and anticipated use of the building rather than simply specifying the highest grade available.
Where Does Pedestal Adhesive Fit In?
The PSA performance grade describes the performance requirements of the complete raised access flooring system. Pedestal adhesive nevertheless plays an important role in maintaining the stability of the installed pedestal structure.
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The adhesive must provide reliable attachment between the pedestal base and the prepared subfloor and maintain that bond throughout the service life of the installation.
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For this reason, pedestal adhesion and installation quality should be considered alongside panel and pedestal performance when specifying and installing a raised access flooring system.
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Testing Pedestal Stability
StarFix pedestal adhesive installations can be assessed using recognised raised access flooring test methods including:
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T42 - P4.06 – Dynamic Pedestal Test (Swing Bag Test)
Used to assess the resistance of an installed pedestal to impact loading.
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T15 - P4.07 – Horizontal Load Test
Used to assess the ability of the pedestal installation to resist horizontal forces.
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These tests provide practical methods of evaluating the stability of the installed pedestal and adhesive system.​ Please see our dedicated Swing Bag Testing and Horizontal Load Testing pages for further guidance.
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PSA MOB PF2 PS/SPU & BS EN 12825
The PSA specification is not the only standard used for raised access flooring.
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BS EN 12825 – Raised Access Floors provides another classification system widely used for raised access flooring. The two systems use different approaches to classification and should not be regarded as directly equivalent.
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Where a project specification refers to a particular PSA grade or BS EN 12825 classification, the specified performance requirements should be checked carefully rather than assuming that one classification automatically corresponds with another.
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Specifying the Correct System
Selection of the appropriate raised access floor should consider not only the immediate intended use of the building, but also foreseeable changes during its service life.
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Factors may include:
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• Occupancy and building use
• Static equipment loads
• Concentrated loads
• Equipment movement
• Data and communications equipment
• Future changes of use
• Floor height and pedestal configuration
• Required design life
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Where there is uncertainty, the appropriate raised access flooring manufacturer, system supplier or project designer should be consulted.
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StarFix – Supporting Raised Access Flooring Performance
StarFix pedestal adhesives have been developed specifically for the raised access flooring industry.
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Our technical resources provide contractors, manufacturers, architects and specifiers with practical guidance covering pedestal adhesion, subfloor preparation, installation, curing, environmental conditions and performance testing.
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The performance of any raised access floor ultimately depends upon the correct specification of the complete system and the quality of its installation.
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