Understanding Raised Floor Systems for the

credits : The Access Flooring Company
Unit 5 Hortons Way
Westerham Kent TN16 1BT

Current Specifications
Current Specifications fall into two main categories: those of the UK
standard which is compliant with MOB PF2 PS and those that are not. MOB
PF2 PS is the adopted standard for UK installations. European standards are
normally determined by the German DIN standard. The main differences
between the MOB PF2 PS and the DIN standard being that for loading
values the DIN standard adopts a safety factor of 2 and the UK standard
adopts a safety factor of 3. The other main difference between the UK and
DIN standards is that the DIN standard requires a more vigorous fire rating
in the manufacture of the materials. All UK pedestals will also have 100 mm
x 100 mm base, whereas the European standard normally calls for a smaller
size. All UK panels will be totally encased in steel. Under the MOB PF2 PS
panels must be designed to last 25 years and the understructure 50 years.
The majority of raised flooring manufactured comes in a standard 600 mm x
600 mm floor panel size.
The MOB PF2 PS calls for three grades of floor. Their relative loads are
listed below:

The systems shall sustain three times the particular static loadings for 5
minutes without collapse with the exception of the 11 kN four point static
load required for the EXTRA HEAVY GRADE which shall be 2 times for 5
minutes without collapse. The system shall be capable of withstanding this
load at any of the positions which has been subjected to the particular static
load test.

Your first decision when specifying should be the GRADE of flooring you
Finished Floor Heights (FFH) or VOID
The next decision you need to make is the height of the raised floor above
your existing slab or sub-floor. This can be expressed as a FINISHED
FLOOR HEIGHT or as a clear VOID space. In the event you specify clear
void space the thickness of the panel will be added to this figure to give the
Please note that when floor systems go above 450 mm it is recommended
that stringers are installed. Stringers are a lateral support between pedestal
heads and their use will result in an increase in the cost. However, I have
seen many installations up to 800 mm with no stringers where the
manufacturer has not installed them, as he has left them as an either/or item
in his quote and has omitted to tell the client that his system is then not
MOB PF2 PS compliant at that height without stringers. This is a common
problem - as a personal recommendation one should insist on stringers above
There are many coverings that can be chosen for factory application to
Raised Floor Panels, some examples are given below. The most common
type of floor panel is a bare finished panel; standard practice is to then finish
with 500 mm x 500 mm carpet tiles laid off grid on a tackifier adhesive.

Installation Environment
The proper installation environment is essential if a good installation is to be
achieved. A good document to specify is the K41 specification in which you
can insert your required Panel GRADE, Finished Floor Height and Floor
Finish. This Document is examined in depth in the link K41.DOC
Non Compliant Systems
There are a number of non-compliant systems on the market and these can
produce significant cost savings over a fully compliant system. They can
provide a good alternative solution to traditional timber and joist
construction. These normally consist of a high density particleboard panel
installed on a pedestal of steel or block, for longevity it is wise to choose one
which has steel adjustable understructure as maintenance can be high on
concrete block installations.
The views expressed herein are those of The Access Flooring Company and are intended
as a guide only and no liability will be accepted for reliance on these views in isolation or
without full knowledge of requirements or specific conditions that prevail for the
particular Project.

Raised Access Floor System Selector

1 What is the application for which your floor will be used ?

2 What is the Loading that will imposed on the floor when in operation ?

3 What is the Height of the Floor above the sub floor ?

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