Temporary demountable structures including tents, marquees and stages
Temporary structures, such as stages, marquees, lighting towers, video screens, temporary grandstands, seating areas etc. are erected at many events each year. Because of the number of people in close proximity, the failure of such a structure could have very serious consequences. This policy will apply to any temporary structure with a floor area 15m2 or more.
Failures of such structures can occur for a number of reasons, such as; design faults, erection faults, adverse weather conditions, component failure and management failings.
Primary responsibility for the structural adequacy of these structures rests with the event organiser. There are no controls under Building Control legislation to deal with such structures, however, the Council as a land owner and /or licensing authority has a duty to consider the health and safety of people at the event and therefore consideration must be given to the safety of temporary structures. In order to discharge this duty, the Council Safety Advisory group (SAG) consult with Building Control for advice and it is necessary for Building Control to consider what level of checking needs to be applied to such structures.
At the licensing or SAG notification stage, it is unlikely that full details of temporary structures will be available, and therefore it is necessary to impose licensing conditions, or SAG approval requirements/conditions. These could be as below;
All temporary demountable structures (TDS) to be erected must satisfy the guidance contained in the document
Temporary demountable structures: Guidance on procurement, design and use.-Third edition April 2007 Published by The Institution of Structural Engineers
Prior to Build - the following documentation should be submitted a minimum of 28 days before the commencement of the event
- A site plan clearly identifying the location of all temporary demountable structures(TDS) over 15m2
- Design Documentation for TDS: should be provided by the designer, to enable the basis of the design to be clearly understood and the design criteria to be verified, and should include as necessary structural drawings, calculations, certificates, statements of loading and specifications including the maximum wind speed that the temporary structure is designed to withstand.
- Evidence of Competence of the Designer; the designer should be able to offer evidence of competence by way of qualification and experience. Evidence of public liability and professional indemnity insurance should also be provided.
- Evidence of an Independent Design Check: evidence that a check has been carried out of the design of any special or non-standard system by a chartered engineer having appropriate skill and experience.
- To help to ensure structures are erected in accordance with the design a simple summary sheet to the calculations clearly identifying important aspects of the design, such as the ballast and bracing requirements and maximum wind speed must be provided by the engineer.
Prior to Event - the following documentation should be submitted prior to the commencement of the event
- Evidence of an Independent Erection Check: evidence that an inspection of the temporary structure has been carried out by a competent person should be provided. Evidence of the competence of the person nominated to carry out the inspection should also be provided.
- Completion Certificate: a certificate or written record prepared by the event organiser to confirm that the independent erection checks have been carried out and that a temporary structure has been erected in accordance with the design drawings and documentation.
At the Event - the documentation referred to below should be submitted a minimum of 28 days before the commencement of the event
- A wind management policy-this should confirm monitoring of wind speed/weather conditions with contingency planning evidenced to safely respond to the eventuality of wind speeds approaching design limits of all TDS.
Once the information required prior to build has been submitted, BCP will consider all material factors in order to determine the extent of any checks considered necessary.
Such considerations include;
- What would be the consequences of failure of the structure? Size of structure and proximity of people should be considered.
- Has the required information been submitted?
- Has the structure been erected previously and was everything found to be in order?
- How clear is the erection documentation?
- How complex is the structure?
- Are there any particular elements of the design that cause concern?
- Is there a wind management policy in place and is there confidence that this will be complied with?
After full review of these factors, it may be considered at one end of the scale that the structural details/ calculations must be independently checked and that site inspections are required, possibly by an independent engineer. At the other end, it may be deemed that no further checks are necessary.
Such judgements will be made having regards to all factors and judgemental decisions should only be made by a suitably qualified and experienced officer rather than placing undue reliance on a crude numerical risk assessment.
For each event it is important that this decision making process is recorded to substantiate and record the decisions made in this respect for future reference.