Documented rolling tests provide a legally secure solution for free-standing facade scaffolding systems and for the user
The highest quality, an exceptionally large load-bearing capacity, and maximum safety characterise ALFIX’s facade scaffolding systems. These attributes were put on display in the test setup for free-standing facade scaffolding systems, conducted in cooperation with the company HEPP GmbH, the Federal Association of German Prefabricated Buildings (BDF) and the DFH Deutsche Fertighaus Holding AG. The well thought-out system solutions with these properties made a strong impression when put to the test.
The client HEPP GmbH is a long-standing partner of reputable prefabricated house manufacturers and often provides scaffolding for prefabricated wooden houses. This is where facade scaffolding systems from ALFIX GmbH regularly come into play, providing scaffolding which functions as roof edge protection scaffold, as it also includes roof safety barriers equipped with inner brackets and protective net supports. One essential customer requirement is to avoid anchoring the scaffold to the house in order to save labour time and ensure a cost-effective operation, while also preventing lasting damage to the facade. Anchoring points often remain weak spots in subsequent thermal insulation, even after they have been professionally sealed, and former anchoring points also remain visible, which make it clearly preferable to avoid using them whenever possible.
Approach
In collaboration with HEPP GmbH and BDF e.V., a legally secure solution for free-standing facade scaffolding with telescopic scaffolding supports was developed. The project began in 2019 with the ALFIX and UNIFIX facade scaffolding systems with a platform height of 3.70 m. Since then, however, the average height of newly built prefabricated houses has steadily increased, which made it necessary to carry out a new test setup with a platform height of 6.20 m.
The required proof that must be provided for a roof edge protection scaffold is detailed in DGUV (German Social Accident Insurance) Guideline 301-001 and includes both the static load impacts as well as the dynamic loads that occur when catching a person falling from the roof.
As part of its approvals for the facade scaffold systems mentioned, the scaffolding manufacturer ALFIX GmbH already provides proof of the suitability of various individual components such as different scaffold decks, safety meshguards and safety net supports for roof edge protection scaffolds. Proof was not previously included for the overall free-standing system of up to 6.20 metres, especially taking into account the dynamic loads from “falling” impacts to maintain stability against tipping.
The mathematical proof, taking into account the dead weight, traffic loads and wind loads, was carried out analytically using the frame analysis software RSTAB. The dynamic load when catching falling people can hardly be depicted analytically, so rolling tests were carried out under realistic conditions based on DGUV Guideline 301-001. Accordingly, a 75 kg roller-shaped test specimen must roll down a flat yet suitable 5.0 m long surface and impact the protective barrier at specifically defined points (at the centre and at the edge of the test roof section). Each point of impact was required to withstand two consecutive impacts without the need to replace damaged scaffolding components. The test is considered passed if the test body is held by the protective barrier and does not fall from the scaffolding.
Test Preparation
The static calculation was carried out for two construction states: for the entirely free-standing scaffolding with no buildings providing shelter from the wind, and for the scaffolding for a closed facade. The calculations showed that in both cases, support must be provided using scaffolding supports which must in turn be anchored to the ground.
When assembling the test setup in front of a closed facade, it is sufficient to attach the scaffold to each support with a ground nail. For the rolling tests, a 12.0 metre high and 10.0 metre long prefabricated house model was built by DFH Deutsche Fertighaus Holding AG on the HEPP GmbH site in order to match the platform height of the scaffold. The scaffolding company ALFIX GmbH provided the scaffolding materials, and HEPP GmbH was responsible for providing the test site as well as the scaffolding assembly. In order to reduce the dead weight of the scaffolding arrangement and thus create the most challenging conditions possible for the practical test, the scaffolding manufacturer selected a greater amount of components made of aluminium, which have a lower load-bearing capacity when compared with steel components (Fig. 1).
Test execution
Eight rolling rests were conducted for each of both the ALFIX and UNIFIX facade scaffolding systems, the purpose of which was to clearly test and demonstrate their stability. For this reason, the scaffolding was secured according to the static calculations for free-standing applications, with two ground nails on the scaffolding supports and ground anchors on the inside of the scaffold. The result of both series of tests was positive: both systems successfully passed the tests and are therefore well-suited for the intended use in this configuration (Fig 2.)
The anchoring support was then gradually reduced until the scaffolds tipped over during the rolling test. Even the ground nails on the scaffolding supports could be left out without creating a significant gap between the facade and the scaffolding or without the scaffolding tipping over. Under the test conditions, the scaffolding supports provided sufficient stabilisation on their own, however, using at least one ground nail per support remains important in order to compensate for unfavourable terrain. Only once the scaffolding supports were removed did the scaffolding tip over when the test body was caught by the protective barrier.
Documentation:
The following documents were created in order to document the results of this project and make the result practical and usable for the user. The corresponding assembly and usage instructions for the ALFIX and UNIFIX facade scaffolding system with scaffolding supports are publicly accessible and can be found under Downloads on the ALIFX homepage.
ALFIX facade scaffolding system, free-standing, including supports
UNIFIX facade scaffolding system, free-standing, including supports
The static calculation and a detailed test protocol were provided to project partners digitally and are available from ALFIX GmbH upon request. Additionally, QR codes linked to the approval protocol can be printed on the scaffold for easy access to this information.
In summary, in close collaboration with the involved companies, it was legally proven that safe construction and use of ALFIX and UNIFIX facade scaffolding systems with a platform height of 6.20 metres is possible, in combination with inner brackets and roof edge protection barriers without the need for anchoring on the facade. To ensure stability even on uneven surfaces, only supports must be attached in accordance with instructions for assembly and use. IT was also proven that the structure assembled using ALFIX and UNIFIX TRBS guardrails has greater stability overall when compared with the same structure constructed using ALFIX and UNIFIX guardrails.
Further information about our products can be found at www.alfix-systems.com/en/
ALFIX GmbH
Langhennersdorfer Str. 15
09603 Großschirma, Germany
info@alfix-systems.com