Some of the most frequently asked questions on access flooring and cable management.

We take you through some of the most frequently asked questions on access flooring and cable management and offer insights from the experts in the industry specialising in this field.

1.    What is a raised access floor and cable management?
A raised access floor is a load-bearing, raised or elevated floor installed above the concrete subfloor in a building, supported by vertical, adjustable pedestals. The void below the floor or plenum thus created provides an environment that can safely accommodate mechanical and electrical services, smoke detection, data and voice services and, in many instances, underfloor airconditioning.

With an increased finished floor height, the plenum can then accommodate more services including cable trays, data and electrical trunking, chiller pipes for under-floor airconditioning and fire detection systems. The access floor can be as low as 90mm but at 37mm – 65mm it is preferable to use a cable management system as opposed to a raised access floor.

This is because at 37mm – 65mm high the access floor panel is 32mm thick thus creating a distance between the concrete floors and the underfloor panel of only 33mm maximum which can’t accommodate anything.

This is where a cable management system is used. Cable management systems are available at heights of 37mm, 60mm, 90mm and 120mm. The panel is only 2mm thick so the installation of under-floor services can work in a cable management environment.

From 90mm upwards cable trays can be used. In many instances at the lower finish floor heights you can fit a jazz matt on the floor and lay the cables on it.

A jazz matt separates sensitive cables from a concrete floor. Ironically, in most of the world they just place the cabling on the concrete floor – cable trays are very much a South African thing.  

Simply put, a raised access floor is designed to go into building designed for access flooring.

A cable management system is not an adjustable raised floor. It’s designed to manage cables. Such a system starts at 37mm high, the panel is 2mm thick, giving you a 35mm clearance, which is the same as the raised access flooring, but now the panels are 21mm by 21mm.

Cable management systems come in 37, 60, 90 120 and 150mm high? and are designed for both new and old buildings. Some buildings are not designed for an access floor and therefore a cable management system would be more suitable. Cable management systems are more expensive than raised access floors. They do however have height restrictions. Access flooring and cable management systems will always play a crucial role in buildings because, even though data may be wireless, water cooling, electricity, sprinkler systems, water chiller pipes and smoke detection will never be wireless.

2.    What are the key components of a raised access floor?
This is very specific to a specification. If you are looking at a specification for a general office environment and the finished floor height is below 900mm, then you would use a Type 1 or Class A multifunctional access floor system, which would be either a steel panel or timber encapsulated steel panel.

Calcium sulphate is rarely used in South Africa, as it is very heavy.

A panel doesn’t necessarily have to be 600mm x 600mm; they are also available in 610 x 610 and 500 x 500. The smaller the panel the higher the concentration of the under-structure.

It does seem that there are cases where higher products are specified than those needed. The access floor must comply with the end user’s requirements and with these requirements in mind an access floor should be specified accordingly. By over-specifying a floor a client’s money is simply wasted.

It is preferable to opt for a multifunctional or dual-function system, as a non-multifunctional system is less adaptive to a client’s future needs, e.g. banks do a lot of churning. With a multifunctional system, for example, you can just use screws and move workspaces. A single-function system means you have to change components and strip a floor, which has significant cost implications. Money is saved by enabling clients to carry out the churning themselves. With old installations, clients would have to call someone in every time they need to do a churn.

3.    What types of raised access floors are available?
•    A steel cementitious floor with a multifunctional head or a dual-functional or single-functional head available in a strap-on stringer system, bolt-on stringer system, screw-down system or free-standing system.
•    A steel-encapsulated wood core panel, either in a free-standing, screw-down or snap-on stringer system. The perception in South Africa is that this is not an acceptable product to be used. However, hundreds of millions of m2 are installed annually all over the world. It all depends on the product that you use.
•    A calcium sulphate panel, as noted above, is rarely used in South Africa as it is difficult to work with and more expensive.

4.    What types of floor panel constructions are available?
There are currently three different panel designs available on the market today:

•    Steel-Encapsulated Wood core panel available also with a high-pressure laminate finish. It consists of high-density particle board. It is a light, versatile and easy-to-use panel. It saves money in airconditioning costs and the costs associated with the time spent on churns. It can be easily cut without use of special tooling for the perimeters and different-sized holes to allow for accessories. The panel provides high strength, good fire resistance and acoustical properties.
•    Calcium Sulphate panel – it is significantly heavier and entirely made of calcium sulphate material. This panel is non-combustible but is very heavy and difficult to work with. The panel provides high strength, high fire resistance and acoustical properties.
•    Steel cementitious panel – used globally. These systems are preferred in Africa as the panel is extremely robust and extremely hardwearing. 90% of all access flooring installations in South Africa make use of steel cementitious panels and installations as old as 30 years are still in good condition today.

5.    How do you increase lateral stability on the floor?
By introducing stringers or screws. A stringer is component in access flooring designed to provide increased lateral stability. It’s a particular favourite for IT environments. In access flooring with over 900mm finished floor height, a stringer will help the fitter to install the floor. It boils down to the following question: What are the requirements on a specific job? They are used for a specific installation where the customer’s requirements are taken into account.

6.    What are the anticipated structural requirements of the raised access flooring in terms of static loads, rolling loads and pedestrian traffic?
Once again it is very client-specific. In South Africa, 90% of all access floors will either meet or exceed SABS 1549.1993 Edition 1.1 / or SANS, MBO (British Standards) & CISCA has far higher load performance criteria and a lot of products are tested to CISCA (US Standards).

7.    What are air plenums and why are raised floor voids used as air plenums?
These are designed for an airconditioning system. The airconditioners are switched off at night and the air trapped in the designed space is cooled by the concrete. During the day the air is recycled into the building via diffusers. In this manner you have created an airconditioned plenum. However, the space is also used for data, power, and smoke detection. By creating an airconditioned plenum, you maximise space, which becomes more economical for the building in the long run. Buildings can save thousands on electricity when an air plenum is used.

8.    How is a raised access floor installed?
It is very client- and need-specific to the construction site.

A raised access floor is set out at 3m x 3m intervals to allow other sub-trades to install their equipment. Materials are then loaded onto the site.

Thereafter, underfloor services take place. This is followed by the raised access floor installation.

Raised access flooring is reliant on a grid line reference, the datum level or height level of the floor, which can be acquired from the builder, and a reputable contractor. The installation will start with four panels; once those are positioned correctly you will continue in a “T” direction.

You then continue building into a square, then into a rectangle, then into a bigger square and a bigger rectangle. As the floor grows, its lateral stability increases and the strength of the floor increases.

9.    Are there any standards governing the use of raised access flooring?
Raised access flooring products should be manufactured under an accredited ISO management system.

Also refer to the SABS 1549:1993 / SANS, MOB (British) and CISCA (American) standards.

Full acknowledgement and thanks go to Jonathan Bates from Bates Access Flooring; Charl Kinghorn, Country Manager at Bergvik Flooring, Clint Hastings, Director at Peter Bates Flooring and Jaco Boshoff, Specifier / Project Manager at PentaFloor Access Flooring for the information contained in this article.