Design of raised floors
Manufacturers now have their own internal design centres where they work on the basis of architects' designs to identify the best technical solutions and supply all system components, from supporting structures to complementary materials.
The finishing material is, in this case, supplied already applied to the panels, speeding up the laying process, which is performed by specialised, skilled teams.
Design
The process of designing a raised floor begins with arrangement of a grid of pedestals and crosspieces forming the system's load-bearing structure (grid system).
In determining the layout of this structure it is important to optimise the number of cuts made on slabs so as to manage format arrangement correctly and make sure that the raised floor does not become uneconomical.
At the design stage it is also necessary to:
- calculate where holes will be needed for accessories: determine what, how many, and where accessories such as pits, towers and grids will be positioned...;
- calculate the loads the floor will be subject to so as to identify the most appropriate structure;
- identifying environmental conditions (such as the possible presence of humidity);
- choice of top surface finish (polished, glossy, semi-gloss, natural, structured).
The product of the design stage is a graphic plan showing the grid system of the raised floor for reference in the successive stages, sealing and laying.
Selection criteria
The flexibility of raised flooring systems permits selection of the perfect components for any situation. The factors to be taken into account at the design stage are:
Mechanical resistance: the capacity of the system (panel + pedestals) to resist stress from loads, which may be concentrated or uniformly distributed.
UNI standards define classification of raised floors on the basis of their ability to resist concentrated loads:
class 1 - use with light loads -> concentrated load2 KN
class 2 - use with medium loads -> concentrated load 3 KN
class 3 - use with heavy loads -> concentrated load 4,5 KN
class 4 - use with special loads -> concentrated load 4,5 KN
Reaction to fire: the modular raised floor, precisely because it can be dismantled, cannot be considered a dividing element for separating the plenum and the room above it.
It must be designed to ensure that in the event of fire:
- the load-bearing capacity of the modular raised floor is guaranteed for enough time to permit occupants to leave the premises safely;
- spread and propagation of fire and smoke will be limited, in accordance with current legislation;
- where required, fire resistance must be 30 on the REI index.
Electrical properties: raised floors react differently to the disturbance created by electrostatic charges depending on characteristics of the material they are made of. A floor may be considered antistatic, that is, capable of preventing strong electrical discharges to people, if it has values of between 1.5x107 and 2x105 ohms.
A floor with values between 1.5x105 and 1.5x107 is considered conductive.
The disturbance caused by electrostatic charges may be eliminated with appropriate choice of finishing materials and by designing the system entirely out of earthed conductive elements.
Soundproofing: the elements that affect noise level in a room when people walk are:
- the density of the panel; calcium sulphate and steel/cement types are high density materials offering superior soundproofing properties
- top surface finish
- height of the structure
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