Raised floor



First of all, the site’s suitability to receive all the materials involved in the installation of the access floor has to be inspected. The site should have the following adequate facilities:

• suitable ways to get to the site by truck
• weather-protected closed site for stocking materials
• keeper
• lifting equipment to bring materials to the floors (crane, elevators)
• adequate access services to introduce materials into the various rooms (access, doors, windows, ramps, etc.)
• adequate power source
• adequate electrical lighting
• the areas where the floor is going to be installed have to be clean and free of materials left from previous works
• false ceiling and eventual sprinkler system (if any) have to be already definitely installed
• external doors and windows have to be already installed
• when necessary, cableways, expansion joints and cracks, have to be sealed
• it is very important to verify the quality of the sub-floor, which should be almost smooth.

Such a finishing can be obtained caring the subfloor casting.
In order to optimize the fulfilment of the work, the technical staff operating on site should give an appropriate support to:
• The installers
• The building management
• The customer



After the inspection, when required, the position of the panels is traced out. This operation, in agreement with the client, is very useful as it allows rapid installation and good esthetical results. The floor layout may be different every time, but some preliminary rules should be followed to obtain better final results.

It is also necessary to calculate the pedestals height, although they are adjustable up to 50 mm, since the level gaps of the floor can be higher than that. Concerning the raised floor height, the range is wider, starting from a minimum height of 10 cm up to about 1 m (and more, with a dedicated design of the columns).


3 - Installation

The floor installation has to be carried out in accordance with the above mentioned conditions. The slab in the room should be cleaned with a vacuum cleaner and painted with a layer of antidust paint, preferably polyurethanic or epossidic types (because they do not alter in the time). This procedure must be absolutely followed when the subfloor void is used as an air-supply/return duct.

There are various installation methods, depending on the experience of the installers and the floor type, in particular if it is with or without stringers. In order to have a reference point, such as an orthogonal axis system, two perpendicular nylon wires are fastened from wall to wall; to calculate their perpendicularity , the Pythagoras’ theorem, or simply 3, 4, 5 method (see fig.1) can be applied.

Point “0” of fig. 1 refers to the starting and reference point of pedestal and panel installation. Once the substructure has been installed, it has to be levelled. For this purpose several tools can be used: 15 metrelong spirit levels, laser levels, optical theodolite, or the more common 3 metre-long rigid levelling rods. Once the substructure has been installed, the panel installation can start too. It is advisable to start from the first row of internal panels along the two orthogonal axes. Make sure that there are not too small pieces of panel on the floor perimeter.

For stringerless substructures, whose bases have to be glued on the slab, pedestals and panels are installed at the same time, with constant levelling. After this kind of installation it is advisable not to walk on the floor during the first 24 hours, in order to let the glue dry out. Once the panels and pedestals have been installed, the final stage consists in installing ramps, steps, upstands and relevant accessories. After the installation, if other works have to be done on the floor, it is advisable to protect the floor covering surface with cardboard or polyethylene sheets.


4 - Installation time

The installation time of raised access floor depends on several factors:
• Installers’ skill and experience
• installation tools
• dimensions, shape and accessibility of the rooms
• type of panel and covering (lower and upper surfaces)
• type of structure

A team of 2 installers can install from 20 to 80 m² of floor per day, depending on the above mentioned factors.
It is important to consider that a lot of time is required for the cutting and installation of the perimetral stringers and panels. Therefore, it is advisable to set the job to skilled installers, equipped with all suitable tools necessary for a proper installation.



Keep free from obstructions all the access roads to the site where the raised floor will be installed, in order to permit the unloading of the materials near the access zones or the lifting machines.

Keep free from obstructions also the horizontal access to the site and to the lifting devices to the floors, in order to permit the easy movement of the materials with transpallet. Appropriate passages for the transpallet have to be arranged where the raised floor will be installed.

It is advisable to define contractually the characteristics and use programmes of the lifting devices for the vertical transport of materials.


6 - Storage on site

The material has to be stored in dry and protected areas, with temperature between 5°C and 35°C and relative humidity between 40% and 75%.


7 - Conditions of the rooms

The raised floor should be installed in rooms with temperature between 5°C and 35°C and relative humidity between 40% and 75%. The building works should have been terminated not less than 30 days before the installation, damp works not less than 15 days. External windows and doors have to be already installed; the slab must be clean and flat. The exact finished floor height must be explicitly indicated.
Before starting the installation of the raised floor, all systems and interior finishes have to be completed, except for the mobile partitions which will be installed on the floor.

In order to guarantee the safety and the quality of the installation, nobody – except for the installer – can walk on the raised floor during installation and, if adhesives are being used, also for 24 hours after installation.


8 - Cleaning the site

The installation includes the removal of all remaining materials on a pallet next to the installed and cleaned floor; it excludes the transport to the base level of the building and the transport to the public dump. After the floor installation and cleaning, it is advisable to protect the floor covering surface with suitable materials in order to avoid impacts, scratches and abrasions during subsequent works. A suitable material is the MDF 2-3 mm thick, or a similar product



The raised floor is tested and handed over as soon as the installation is completed, before the application of protection materials (recommended),and other system installations.


10 - Final control

Procedure and acceptance criteria of the final control on site.

After the installation, the raised floor has to conform to the following parameters:
• allowed deviation of the alignment of the gaps between panels ± 3 mm
• allowed level gap between adjoining panels measured near the edge (uncharged panels) ± 1 mm
• allowed level gap on all the surface of the installed raised floor ± 6 mm
N.B. except for other dispositions of the Customer Site Manager, related to connections with doorsteps and other floors.
• perimetral cuts: maximum gap allowed between cut panel and wall or other perimetral elements to be cut ≤ 10 mm.
• panel stability: the panel has to rest on at least 4 points, (excl. perimetral adjustments) with allowed tilting ± 1 mm, measured alternatively on two opposite corners of the uncharged panel.

Guide to the installation of raised floor

The following general instructions are valid before every raised floor installations.

1. Make sure that the slab is suitable to support the chosen substructure. Generally speaking, it can be said that the more regular the slab, the easier the installation and the better the final result.

2. Make sure that the room where the raised floor will be installed is free from remaining materials and perfectly clean.

3. Check that all brickworks have been completed some time before the installation in order to not have moisture.

4. Check that complementary installations, in particular the external frames, have been completed.

5. When required, verify that the slab has been treated with anti-dust primer.

6. Check the materials in order to determine if something is missing.

7. Determine the lowest and the highest point of the room so as to be able to calculate the height of the pedestals.

8. To reduce the possibility of mistakes it is advisable to start with an area not exceeding 100-200 m²; nevertheless, the quantity may vary according to installer’s experience.

9.Also for substructures with stringers it is sometimes necessary to fasten the bases to the slab either with glue or screw anchors, for example in the following cases:
• height over 60 cm,
• near the joints
• in case of floor without contrast perimetral walls (e.g. curtain walls)
• whenever a better stability and stiffness of the raised floor is required.