Stages and temporary structures: stability verification and testing after the Italian “Stages Decree”

What the “Stages Decree” changed

The Interministerial Decree of 22 July 2014, published in the Italian Official Gazette no. 183 of 8 August 2014 and known as the “Stages Decree”, implemented art. 88(2-bis) of Legislative Decree 81/2008, extending Title IV (temporary or mobile construction sites) to the sector of musical, cinematographic and theatrical performances and trade fair events.

Its scope covers the assembly and dismantling of temporary works, the installation and removal of audio, lighting, video and stage technology systems, and the ancillary operations of loading, unloading and handling equipment. Technical and organisational instructions were issued with Ministry of Labour Circular no. 35 of 24 December 2014.

Why structural verification is not a formality

The temporary nature of an installation does not reduce the actions the structure must withstand. A stage with roofing, towers and sheeting behaves like a sail: wind action can generate forces and uplift far greater than the vertical service loads, and it is the recurring cause of failures at outdoor events.

Verification must therefore be as rigorous as for a permanent structure, taking into account some aspects specific to temporary installations:

• environmental actions (wind and, where relevant, snow) assessed to the Italian code NTC 2018 for the site and for the actual duration of the installation;
• the real service loads: audience, performers, equipment suspended from trusses and towers, audio and video systems;
• the actual restraint conditions at ground level: anchorages, ballast, bearings on ground or paving that are not always adequate;
• the match between design and what is built, often critical in modular structures assembled to tight schedules by different crews.

The documentation required

Document	Content	Prepared by
Design and calculation report	Stability verification of the structure under service loads and environmental actions	Qualified engineer
Correct assembly declaration	Statement that the work has been assembled in accordance with the design and the manufacturer's instructions	Qualified engineer / assembly supervisor
Testing of the temporary work	Final verification of the structural adequacy of the installed structure	Qualified engineer
Documentation for the supervisory commission	Set of documents required for the structure to be approved for public events	Organiser, supported by the engineer

The documents actually required depend on the type and size of the installation, on the presence of an audience and on the requirements of the local public entertainment supervisory commission.

The most frequent mistakes

Reusing a “standard” calculation report. The supplier's calculation applies to one specific configuration: changing span, height, roofing or installation area means changing the design actions.

Underestimating anchorages. The structure may well be verified, but if ballast and anchorages are not sized for wind action the chain breaks at its weakest point.

Postponing verification until assembly is complete. Critical issues must be identified at design stage: intervening when the structure is already up, hours before the event, costs far more and is not always possible.

How we support clients

Stefano Luise Engineering S.r.l. provides stability verification and testing of stages and temporary structures: structural calculation to NTC 2018 with analysis of environmental actions, verification of anchorages and ballast, site visits during assembly, correct assembly declaration and documentation for the supervisory commission.

Regulatory references

Italian Decree of 22 July 2014  •  MLPS Circular no. 35 of 24/12/2014  •  Legislative Decree 81/2008 (art. 88(2-bis), Title IV)  •  NTC 2018

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