A Newsletter from CROSS-UK containing reports on structural safety issues.
Note: this Newsletter was published by CROSS (Confidential Reporting on Structural Safety). Since March 2021, Confidential Reporting on Structural Safety is renamed Collaborative Reporting for Safer Structures (CROSS).
Stability compromised in school hall
A reporter highlights construction issues that occurred during the construction of a new school hall.
School roof timber truss collapse
A gym/assembly hall roof to a school collapsed suddenly and without warning overnight when fortunately the building was unoccupied.
PV solar panels
This reporter queries whether enough attention is being paid to the loads applied by PV (Photo Voltaic) solar panels added to roofs.
Solar panels and effect on snow slides from roofs
A reporter writes in connection with report 246, which discussed dangerous snow slides from buildings, and asks if any of the roofs had solar panels?
Collapse of proprietary timber roof
A proprietary timber roof system spanning 8m over a school hall collapsed. The roof was constructed in 1959, and formed from a ply-web beam system, with hardboard ceiling and ply deck and asphalt covering.
Licensing of temporary structures
Temporary structures, such as stages, marquees, lighting towers, video screens and the like are erected at a huge number of events in the UK each year. A reporter who inspects many such structures raises concerns that the systems in place for ensuring their stability are not working.
Loading from solar panels
A reporter inspected a roof to discover that the structure was already overloaded with the self weight of the roof covering without the addition of solar panels.
Concern about PV installations
A reporter who has been pricing PV installations for portal frames would like to draw the attention of CROSS to concerns regarding issues that are emerging within the industry.
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In this Newsletter, reports 266, 269, 280 and 287 refer to PV installations. Several BRE publications give guidance relevant to these reports: Digest 495 Mechanical installation of roof-mounted photovoltaic systems 2005 Digest 489 Wind loads on roof based photovoltaic systems 2004 Information Paper 8/11 Photovoltaic systems on dwellings: key factors for successful installations 2011 These are available from www.brebookshop.com In addtion, there is the NHBC Foundation publication (written by Paul Blackmore, BRE) NF 30 Guide to installation of renewable energy systems on roofs of residential buildings 2011 This is available from www.nhbcfoundation.org
Report 276 Licensing of temporary structures
I could not disagree with some of the comments however I would expect the duties under the Occupier Liability Act 1957 to apply with the authority being the occupier or controller of the premises and hence holder of any duty of care. The items are certainly structures, are of metal or similar and are non-domestic and are constructed in the 'furtherance of a business' or in line with 'the conduct of their undertaking'. The people who erect and maintain them are at work therefore I would expect the Health & Safety at Work Act 1974 to apply including regulation 3(1) would apply. Although not necessarily notifiable, the construction (Design & Management) Regulations 2007 wherein designer duties under Regulation 11 would apply together with contractor duties under Regulation 13. It would seem that where there is concern there should be sufficient legislation in place to allow the serving of a Dangerous Structure Notice under the building Act 1984 Armed with this information it would seem reasonable for a level of encouragement be given to have matters rectified.I do not advocate a legislative approach in the first instance and usually seek co-operation and discussion but it is nice to know the law should there be a need to encourage when, on occasion, those that can, and perhaps should, do something claim they cannot.
Reports 266 PV solar panels and 280 Loading from solar panels
I am currently working with a large energy organisation on installation of PV panels and cn confirm that not only is a part of the process the need to carry a structural survey on the roof for ability to take both positive and negative pressure loads but also on a number of sites, roofs have required strengthening or been excluded from the programme. (I commend this company on ensuring such checks are carried out). The issue of snow load adds a further issue in that panels can cause a dam effect under slight thaw and instead of the snow sliding off it can be retained against panels and re-freeze overnight to ice. This not only increases dead-loads but at a point of thaw when the ice melts to a sufficient thickness to pass beneath the panel, has the potential to slide off in a single sheet of significant size and weight therefore the accessibility to persons by doors or paths beneath has to be considered. Such systems etc. will remain an issue as so much of the controlling legislation refers to 'non-domestic premises'. 'furtherance of a business' and 'at work' which so often do not apply to residential properties. (albeit civil law may)