Picture courtesy of www.accessflooring.com

American Students should concentrate on the pages with the USA/Canadian flags shown at the top. It is recommended you read the AS/NZS Standards for additional good practices of installation techniques. You must use your local standards as specified in any contract. Note that there are minor variations between the NEC and CSA electrical codes. Ensure you use the appropriate codes in your local area.

Access Floor
A flooring system that consists of a raised floor, supported by a system of vertical and horizontal supports and removable tiles. The tiles allow access to the space under the flooring system for the storage and routing of cables.

There is a variety of support equipment that may be located below the flooring such as raceway and tray for the placement of cables. All fire-stop assemblies shall retain their integrity if penetrated by cables.

Types

Stringered
Access floor (raised) systems which employ a lateral bracing unit between the pedestal supports. Stringers allow frequent removal of panels by providing additional support. Stringers shall be fastened to the pedestal head.

Free standing A raised flooring system which employs pedestal supports as the only form of support. Free standing flooring systems are restricted to finished heights of no less than 150mm (6") and shall be restricted to finished floor heights of 300mm (12").

Cornerlock
Cornerlock access floors are similar to freestanding types but have panels only supported by the pedestal. The panels are mechanically fastened to the pedestals.The panels must be fastened to the pedestals at each corner.

Loading Performance and Testing
Loading performance parameters can be found in Annex B of the original standards document. Panels and understructure shall be tested and meet the requirements of Ceilings and Interior Systems Construction Association (CISCA-USA) test methods (Ref D.12).

These tests take into account the following:

• Dynamic or rolling loads on castors or wheels.
• Static loads which may be point loads, uniform loads or concentrated loads.
• Impact loads such as in an accidental impact.
• Static Electricity discharge capability.
• Acoustical properties for sound proofing.
• Ducting capabilities, tray or ladder fixtures

Fire Rating
Floor panels (not including covering) shall have a Class A flame spread rating (USA rating). Panels shall be made of non combustible materials when cabling is not in conduit. Cutting of the panels shall not affect the flame spread rating.

Seismic Considerations
If this issue needs to be considered contact local authorities for guidance as to any additional structural considerations. In Australia you may also refer to AS 1170.4.

Building Structure

Depressed Slab
In cases of a new construction a depressed slab shall be used for access flooring. A depressed slab is a construction technique where the initial floor level is lower than the finished floor. The depth of the depression is equal to the finished level of the floor.

Normal Slab.
If an access floor is to be built on an existing normal slab then consideration will need to be given so persons and equipment may easily and safely gain access to the raised floor by use of ramps or steps. Building codes shall be followed for both ramp and step assemblies.

Design Guidelines and Procedures for Access Flooring

Work Areas

Penetrations through the floor shall:

• Not be placed in a way so as to create hazards to the occupants.
• Take into consideration the type and number of work areas and may be located anywhere on the access floor.

Specific Design Information

Minimum Height

• General office 150mm (6”)
• Telecommunications room 300mm (12”) not less than 150mm (6”)

Where Heating, Ventilation and Air-conditioning (HVAC) is used in the plenum, the air handling space beneath the floor surface then the minimum height of the access floor shall be 300mm (12").

Cable Management

Shall be provided by one, or all of:

• dedicated routes
• zone distribution system
• raceway primary distribution
• cable tray

Installation

Layout
Floor layout shall be determined prior to the installation of any equipment or telecommunications cabling.

Linkage to Telecommunications Closet
Telecommunications closets and access floor area served should be located adjacent to each other and connected by threaded sleeves or conduits.

Service Fittings
The manufacturer shall be consulted to ensure comparability of the service fittings.

Grounding and Bonding Access Flooring
Consult the manufacturer’s instructions. Also see Annex B.5 in the original standards documentation.

Access Floors Addendum 3

Pathways shall be firestopped according to local codes

Types of Access Floors

• Low profile
• Standard height profile
• Stringered
• Free standing
• Cornerlock
• Integral

Loading performance is provided in Annex B of the original standards documentation.

Testing shall be done as per CISCA test methods, reference D.11.

Building Structure

Depressed Slab

• the slab shall be depressed to a depth equal to the height of the floor.

Partially Depressed or Normal Slab

• provisions for ramps and/or steps shall be made in accordance with ADA. Steps and ramps shall meet local building codes.

Design Guidelines

Work Area Service Fittings

• shall not be placed in traffic areas
• shall not be placed where they could create a hazard for the occupants

Clearance

• under an access floor shall be 20 mm (.75 in) from the bottom of the access panel to the slab or original floor.
• A minimum of 645 mm² (1 in²) cross sectional area shall be provided per work area
• A minimum of 20 mm (.75 in) between the top of an electrical raceway (if used) under the access floor and the bottom of the access floor.
• Finished floor height in a telecommunications room shall be at least 150 mm (6”).

Cable Management
Some form of cable management shall be used, examples are:

• Dedicated routes
• Raceway distribution
• Zone distribution
• Cable tray

Installation

• No equipment shall be placed prior to the access floor layout being known
• Linkage to telecommunications rooms shall be provided
• Sizing shall be determined in accordance with the type and size of pathway used
• Fittings shall be compatible with the access flooring
• Grounding and bonding shall follow all applicable codes and manufacturer’s specifications.

I would like to thank "cablingdB.com" for relevant information regarding the USA and Canadian Standards. Please visit their site for more information regarding the American Structured Cabling Standards.