A TEMPORARY ROOF, measuring 52 metres long x 42 metres wide, has been installed at a Ministry of Defence (MOD) army camp as part of a project to improve soldiers’ accommodation.
The temporary roof installed at Tidworth is part of the £15bn Tidworth and Bulford infrastructure framework. It will improve a number of MOD sites by providing high quality, fully serviced and purpose-built living and working accommodation. The project will ensure that service personnel returning from demanding operations will receive quality accommodation.
To ensure the building remains weatherproof and to enhance its whole life performance, the entire roof is being replaced at Tidworth. Scaffolding suppliers, George Roberts Ltd supported the scaffolding contractor, Ideal Scaffolding Southern Ltd to install the large scale bespoke temporary UBIX roof. It will allow unhindered re-roofing along with access for internal works to replace the ceiling in the main building.
Securing without Ballast
During the first stage of the project, the goal was to erect the internal birdcage measuring 37m long x 18m wide x 12m high using over 250 tonnes of scaffolding, within 3 weeks. The first stage of work happened during the first Covid-19 lockdown, so care had to be taken to observe guidelines. This proved challenging in maintaining social distancing, in particular when working at height.
The second phase of the project was to erect a temporary roof measuring 52m long x 42m wide with additional buttresses for an unsupported span of 38.5m in the centre section of the roof.
A unique ‘Platypus’ percussion anchor point system was used to secure the free-standing structure at ground level. The anchor shaved weeks off the build programme, which otherwise would have required around 450 tonnes of ballast at the base of the scaffolding around the perimeter.
Assembling the Largest Temporary Roof
Due to the sheer size of the truss beams, the roof bays had to be skillfully assembled at ground level. This was done on special rigs by Ideal Scaffolding Southern Ltd, then lifted into position on top of the support scaffold by a crane. This meant the roof was assembled, lifted into position (over a three-lift programme) and fully sheeted in situ over a staggered four-week period to maximise safety and productivity.
The Keder roofing sheets supplied by George Roberts were manufactured exactly to size. They used a 610g/m flame retardant PVC material providing a watertight barrier, meaning roofing works were protected from the weather and need not be interrupted by bad conditions.
The X Factor
Because of the very large 42 metre span on this project, a heavy duty 1.3m deep X Beam was specified, which was a first for George Roberts and Ideal Scaffolding. Without X Beams the project wouldn’t have been possible.
George Roberts called on the services of Alan White Design and its licensed beam manufacturers Apollo. The companies expertly engineered the brand new 18-degree Ridge Beam to form the main duo-pitch roof truss structure. They also produced the design for the bespoke aluminium diagonal brace and tension bar system to strengthen this gigantic free-standing structure.
The main challenges for George Roberts Ltd was to rapidly supply over 250 tonnes of equipment. It was transported the 200 miles to the Tidworth site from its Liverpool depot over multiple loads.
There were also engineering challenges due to the size of the building and roof span required. Tying into the structure was not permitted, meaning all supporting scaffolds needed to be free-standing.
The Tidworth and Bulford project represents a significant investment which will ensure service personnel continue to have access to high quality facilities on the defence estate.
The whole project comprises earthworks, groundworks, drainage, reinforced concrete works for foundation slabs and external works to various types of accommodation blocks. Associated external works include access roads, footpaths, car parks, hardstanding, street furniture and lighting, bin stores, cycle racks and areas of hard and soft landscaping.
Largest Temporary Roof Stats
- The overall plan cover size exceeded 2000m²
- The building was over 40 metres in width and all supporting scaffolding had to be completely free standing.
- Temporary roof covering was a whopping 52m long x 42m wide.
- Each of the 19 trusses weighed up to 2.6 tonnes.
- More than 250 tonnes of scaffolding equipment were delivered to site.
- The structure was fully weather contained in situ and the sheeting material was tailored to length to provide an exact fit.