Two norms govern the manufacturing and the installation of the raised access floors.

• The NF norm DTU 57.1 defines the conditions of implementation of the raised access floors. This norm was modified in September, 2007. As all DTU, the standard 57.1 includes 3 parts called P1-1, P1-2, P2.
• The NF standard EN 12825 treats technical characteristics of the constituent elements of a raised access floor (panels, pedestals, stringers) and defines the methods of measure and tests. This norm was born in January, 2002 and was adopted by the majority of the European manufacturers.

These norms are available, to order, with the organism of management of the norms. However, you will find there below, the most important extracts.

A] P1-1 : Conditions of the implementation

1.1 Required general tolerances

• Finished level : <= 5 mm,
• Horizontality : maxi 3 mm on a surface of 5 m x 5 m,
• Flatness : < 2 mm under the rule of 2 metres,
• non emergence between 2 neighboring panels : < 1 mm,
• Understructure with stringers for a finished height > 500 mm,
• The raised floor must be conceived to allow the removal of the panels,
• For the earthing, a network of copper braid binding a certain number of pedestals between them, must be realized.

Precisions concerning the electric and acoustic resistances are also given.

1.2 The coverings

• Textiles : coverings in class 3 or 4 (according to NF IN 1470) are allowed,
• Ductility : coverings class 32 (according to the NF standard IN 685) are allowed,
• Sets : must be exchangeable, present neither join nor centring,
• Removal loose lay tiles : have to respect the DTU 53.1 and 53.2.

1.3 Installation

• The rate of humidity must be measured and applied according to the NF standard DTU 53.2,
• The glazings must be put, premises shielded from the bad weather, a re-humidification of places does not have to be any more to be afraid,
• Additional specifications are mentioned for the resistance of the low support, their states of surface, as well as for treatment anti-dust (NF DTU 59.3).

1.4 Conditions of construction site

• The teams of installation store the material, under cover,
• The ambient temperature must be included between 12 and 24°C,
• The relative humidity must be included between 45 and 70 %,
• The concrete support of the raised floor must be exempt from concrete remains, the harshnesses have to fill again, she must be exempt from any object, clean and dusted,
• No other traffic than of the team of installation must be made during the intervention and 48 hours after the installation,
• The level of 1 m finished must be present and correctly identify to allow us to make the statements of levels.

1.5 Finishes

• The level of panels is verified, they must be correctly tightened before the implementation of the border panels,
• The company has to clear the trays of any falls and pallets,
• The pre-reception of the work is imperative according to the contradictory report planned for that purpose in the presence of the Project Owner and of his representative.

B] P1-2 : Constituent elements - general criteria of choice of materials

This part informs us :

• That the metallic materials have to be subjected to a treatment of protection,
• Of the nature of materials composing panels, pedestals, stringers, etc…
• That coverings of all kinds have to satisfy to their norms of custom…

C] P2 : Constituent elements - Document of the special clauses

This part specifies the consistency of the works and their coordinations :

• The list of due works and the works not planned (IMPORTANT !)
• Which are the necessary information for the works ?
• The acceptance of the works,
• The not planned interventions,
• The contradictory report of the end of assembly.

1] The deflection under load

1.1 Safety factor

The majority of the European manufacturers privilege the safety factor of 2, the coefficient 3 is used only in exceptional cases.

1.2 Deflection class

• During the choice of a raised floor, the architect has to choose the class of deflection which he wishes to obtain. It is here a notion of elasticity of the system that is looked for
• Do I admit that my system deforms of 2,5 mm for a load of X (class A), or may I tolerate a deflection of 3,0 mm or 4,00 mm ?
• The majority of our customers ask for a class A, extremely stringent to the detriment of the class C, the most tolerant.
• When we walk on a raised floor, it is natural to have a product resisting well to the effort and not to meet itself on one trampoline.

1.3 Load class (with a safety factor of 2) - (1 daN = 1 kg approx.)

If you authorize a load about 300 kilos (3 kN) on the system, in some point, then the system will have to satisfy tests of ultimate load of 2 x 300 = 600 kilos !

In summary, a manufacturer indicates you that its system is classified 2A for example with a safety factor of 2, it means:

• that the system broke in various points of test of load in 600 kilos values at least
• that the system resisted in various points of test of load to a load of 300 kilos and that the deflection has never exceeded 2,5 mm this moment there!

Others examples :

1A: the system resists to 200 kg, the break is superior to 400 kg, the deflection does not exceed 2,5 mm for 200 kg

6A: the system resists to 600 kg, the break is superior to 1200 kg, the deflection does not exceed 2,5 mm for 600 kg

3A: the system resists to 400 kg, the break is superior to 800 kg, the deflection does not exceed 2,5 mm for 400 kg

3B: the system resists to 400 kg, the break is superior to 800 kg, the deflection does not exceed 3,0 mm for 400 kg

3C: the system resists to 400 kg, the break is superior to 800 kg, the deflection does not exceed 4,0 mm for 400 kg

1.4 Carrier elements

The carrier elements of the raised floors (called generally "pedestals") have to resist to an equal load with 4 times the acceptable load..

The effort axial was measured as previously in a speed of 12 dan /sec with an awl of 50 x 50 mm, centred on the high part of the element.

2] Tests of impact of a hard body / of a soft body

These tests arise from foreign standards and connected since with the present standard.

2.1 Hard body

A weight about 4,5 kg, cylindrical in its extremity, is released 600 mm in height. He must be mentioned on the test report (PV of test) if the system resisted to the shock and the observed deformations.

2.2 Soft body

A sandbag of a weight about 40 kg, flat in its extremity, is released 1000 mm in height. He must be mentioned on the PV if the system resisted to the shock and the observed deformations.

3] Dimensions

Have a system which resists to the load, it's good, but to have a system which also insures the interchangeability of elements in the time, it is also very important!

It is for that reason that the standards include the dimensional tolerances of the systems and, in particular, the horizontal elements, the panels !

The dimensions are characterized by the quotations taken on the sides of panels, but also the square of the panels. The norm defines a specific method for these measures. They must be measured and expressed in 1/100 mm, with instruments calibrated, connected with the national channel of calibration.

The dimensional tolerances of the norm are the following ones :

The respect for these quotations is extremely important !

4] Others technical characteristics

The NF standard IN 12825 also describes the requirements in :

• Corrosion
• The Resistance in the coat of covers PVC, linoleums (flexible)
• Reaction to the fire (IN 13501-1)
• Fire resistance (IN 13501-2)
• Electrostatic conductivity (EN 1081)
• Risks of electrocution
• Sound attenuation (NF EN 10848-2)
• Conduction of heat

We remind you that the norm is available with accredited bodies of distribution such as the AFNOR (FRENCH NATIONAL ORGANIZATION FOR STANDARDIZATION) (http://www.afnor.org).