There is one key difference in practical use: although commonly referred to as a mobile scaffold, according to the applicable standards it is not scaffolding, but a mobile work platform. DIN EN 1004-1 refers to mobile work platforms made of prefabricated elements. Mobile work platforms are defined as single-span constructions made of system-dependent components with specified heights and widths. Mobile scaffolds, on the other hand, are mobile constructions that consist of scaffolding components. In Germany, mobile scaffolds are regulated by DIN 4420-3 Service and working scaffolds – Part 3: Selected types of scaffolding constructions and their basic versions. They can consist of several spans of scaffolding. Mobile work platforms mostly take the form of mobile aluminium scaffolds, while mobile scaffolds are made of steel.

What this means in practice: Mobile scaffolds in accordance with DIN 4420 must be planned and erected by scaffold erectors, while mobile work platforms in accordance with DIN EN 1004-1 may be erected by trained, specialist persons.

DIN EN 1004-1 decrees that mobile scaffolds in the form of mobile work platforms may consist of one span only. Mobile scaffolds must be designed in such a way that they can be assembled, converted and dismantled without the need for personal protective equipment to prevent falling. In mobile scaffolds, only one deck surface may act as the work platform. This is generally the uppermost platform. Levels below this are intermediate platforms. According to the new, revised standard issued in 2021, the distance between the platforms may not exceed 2.25 m, and the vertical distance between the ground beneath and the first platform may not exceed 3.40 m. How high can a mobile scaffold be? The height of the work platform may be maximum 12 m inside a building and maximum 8 m outside a building. As a rule, inner ladders must be present as part of the structure. Outside, climbing up to the work platform is not permitted. Furthermore, mobile scaffolding may not be used as access to or an exit from other structures.

Scaffolding is divided into seven classes for width, two classes for headroom and six load classes. This division and classification also partially apply to mobile scaffolds as mobile work platforms.

In the standard, the width class is indicated by the letter W and two numbers. The seven width classes range from a width of 0.60 to 2.40 metres, in increments of 30 centimetres.

In Germany, system scaffolding generally conforms to height class H1 (headroom of less than 1.9 m in the area of the frame). If the headroom is 1.9 m or more, height class H2 applies.

The load class defines the maximum possible uniformly distributed load in a scaffold span (surface load q1 in [kN/m²]) or the maximum possible concentrated loads on defined surfaces (single load F1 on a surface measuring 500 x 500 mm or single load F2 on a surface measuring 200 x 200 mm). The selected load class must be suitable for the type of work to be performed. Load classes relevant to mobile scaffolding:

• Load class 1: Use for inspection work only (max. uniformly distributed live load q1 = 0.75 kN/m²; concentrated load F1 = 1.5 kN or F2 = 1.0 kN)
• Load class 2: Use for work that does not require any storage of building materials or components (max. uniformly distributed live load q1 = 1.5 kN/m²; max. concentrated load F1 = 1.5 kN or F2 = 1.0 kN)
• Load class 3: Use for work that does not require any storage of light building materials or components (max. uniformly distributed live load q1 = 2.0 kN/m²; max. concentrated load F1 = 1.5 kN or F2 = 1.0 kN)

How many people does it take to erect a mobile scaffold? This depends on the mobile scaffold’s basic design. Thanks to their consoles for ladders, which can carry all the individual components needed, and the so-called 3T method – or the integrated railings all round in the case of the FlexxTower SG – single-person scaffolds such as the FlexxTower can be erected by one person.

However, two people are needed for most mobile scaffolds to ensure safe assembly. Components need to be handed from one person to another, held and fixed in place. To ensure that no one is injured, at least two people are required – and three or more for higher scaffolds.

For erecting a mobile scaffold, it is important that the surface has sufficient load-bearing capacity. Mobile scaffolds can be erected on screed or other concrete floors without problem. Tarred or plastered surfaces are also highly suitable. What’s important is that you erect the mobile scaffold plumb on a level surface (maximum inclination 1% or 0.57°). On natural ground, the castors can sink in and jeopardize stability. In this case, it is essential that you place suitable boards or planks underneath, which will distribute the pressure over a larger area.

With mobile scaffolding of a low height, its base area and centre of gravity are mostly all that are needed to keep it stable. In all cases, mobile scaffolds must be secured against unwanted movement by activating the parking brakes. Mobile scaffolds with chassis bar offer additional stability and are also easier to move. This enlarges the base area and enables a choice of two setups when assembling: in the centre or on the side of the chassis bar. Outriggers are another means of improving the stability of mobile scaffolding. These are fitted to the four corners and support the structure. Mobile scaffolds require the right kind of ballast to suit their height and type of setup. The ballast weights must be made of solid materials and be secured against unwanted movement. Liquids or granular materials are only permitted if they are inside special, suitable containers provided by the manufacturer.

The difference in the maximum installed heights of 12 m inside a building and 8 m outside a building is primarily due to the fact that outdoor mobile work platforms may be exposed to wind load.

DIN EN 1004-1 states that wind loads of up to 0.1 kN/m² have to be taken into consideration. The figure 0.1 kN/m² refers to a wind speed v_p of 45.5 km/h or 12.7 m/s and is equivalent to force 6, i.e. a strong wind, on the Beaufort scale. For this reason, different ballast is required for indoors and outdoors. While high indoor scaffolds may require only a little or even no ballast, outdoor scaffolds of an identical height may already need 100 kg or more. This issue demonstrates the importance of the expertise required, correct erection in accordance with the manufacturer’s instructions for assembly and use, and a final check by a person qualified to perform inspections. Moreover, the instructions for assembly and use also contain information on the permitted wind force when moving a mobile work platform out of doors.

The instructions for assembly and use must be included in the scope of delivery of the mobile work platform. The current standard DIN EN 1298 – Mobile access and working towers – Rules and guidelines for the preparation of an instruction manual – from 1996 will soon be replaced by the revised DIN EN 1004-2:2022. According to this new version of the standard, information must be provided stating that the instructions for assembly and use must be available at the mobile work platform’s location of use and must contain the following information, among other things: “This mobile access and working tower may only be used in accordance with the unchanged information in this instruction manual.” Furthermore, all mobile work platforms are governed by the essential safety instruction that no persons or loose objects may be on the mobile work platform while it is in motion.

DIN EN 1004-2:2022 also contains some new requirements. In addition to the text, instructions for assembly and use must also make use of safety information symbols. Examples of symbols can be found in Annex A of the standard. In addition, it is recommended to mark or secure safety information on and to the product. The standard contains symbols for the following warning instructions, for example: