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Help for the specifier - PSA or BSEN

Historically the raised floor industry here in the UK have used the PSA MOB PF2 PS as the bench mark standard for raised flooring. This standard has been used for the last 20 years as a way of defining various grades of raised floor loadings. This was divided into four structural grades of Light, Medium, Heavy and Extra Heavy, with light for general office usage through to Extra Heavy for Main Frame Computer rooms.

Over recent years there has been a tendency to reduce loadings for raised floors, the most commonly specified PSA Medium Grade floor often is over specified for the actual usage of the space. A Medium Grade floor can carry loads of up to 35kN/m, yet often the structural floor it stands on are being designed for 4kN/m. Whilst this may give the owner comfort of it's loading capacity, ultimately it is the building user who foots the bill for this over specification.

Building design, improved materials and enhanced product development over the last 20 years means that modern raised floors perform far better than those of previous years.

With the influx of overseas manufacturers now coming into the UK market, where PSA standards were not used, the introduction of BSEN 12825 fundamentally changes the method of testing and classification to provide the specifier flexibility to determine expected actual loadings and therefore choose the appropriate floor.

In 2001, a European standard, BS EN 12825, was introduced by CEN (European standards body) as a voluntary standard with a view to it becoming mandatory within a five year period. BSEN 12825 has now become widely accepted and adopted by the industry as superceeding the previous PSA graded system.

This should not be considered to be a "lessening" of performance but more ensuring that the correct performance specification is requested.

The classification of each floor has also changed and is now based on ultimate load, ie. when failure of the panel occurs. The floor systems are now classified under four categories; Ultimate load, safety factor, deflection under working load and dimensional tolerances. The introduction of this new standard does provide greater flexibility to the specifier to sub-divide the classifications as certain criteria may be more important than others. What BS EN 12825 does not try to do is advise which system would suit different applications, which means the responsibility of ensuring the correct floor is specified lies with the specifier or architect. Until the changes become properly understood by the industry, we would recommend that guidance is sought early on from MERO to avoid costly mistakes.-


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