Context 144 - May 2015

C O N T E X T 1 4 4 : M A Y 2 0 1 6 19 JOHN RUDDY Scaffolding historic structures Successful scaffolding of a historic building depends on minimising the damage to the fabric by understanding the historic significance, planning ahead and good communication. Any scaffolding project involves working within various constraints, such as practicality, cost, safety, conforming to industry standards, and functionality. With historic building projects, there is another constraint that needs to be firmly in our minds: the need to protect the historic fabric. This encompasses not only protection fromminor damage, but from considerable harm too, for example due to the failure of a propping scheme, or the overloading of a historic structure from a scaffold above. Hence at the outset of a scaffolding project it is important to understand the building, and what it is about it that gives it its historic significance, in order to begin to think about how best to ensure that the scaffolding can be designed and installed while protecting the building. Scaffolding is traditionally considered to be temporary works, and as such the responsibility for the design lies with the contractor. For simple scaffolds it is usual for the scaffolding subcontractor to take responsibility for the design, following good practice and recognised industry standards. As the scaffold becomes more complex, calculations and drawings are produced by the scaffold designer, typically working to the National Access Scaffolding Confederation’s Good Practice Guidance for Tube and Fitting Scaffolding, TG20:13, currently £1,206 per copy to non-members. Communication between the project engineer, who hopefully understands the historic significance of the building, and the scaffold designer is a key factor in this process. Often a performance specification document is used to ensure that the historic constraints for the scaffold are incorporated into the tender process. Once the scaffold design is produced, the scaffold designer needs to ensure that the project engineer is aware of any significant loads imposed on the structure from the scaffold.This may lead to the need to assess areas of the structure to confirm any higher-than-anticipated loads can be accommodated, or to consider back propping or other modifications to avoid the risk of distress to the historic fabric. With highly complex scaffolding requirements, one option is to bring the scaffold design forward of the main contract, so that a fully designed scaffold proposal can be issued with the tender documents. However, this can be too prescriptive, given that different contractors have different expertise and approaches, and may wish to undertake the scaffolding in a different way to the design they are given. St Cuthbert’s Church, Brattleby, Lincolnshire This Grade II* listed church is of Norman origin, with the west end tower dating from the 15th century. An St Cuthbert’s, Brattlebury: instead of being tied to the tower masonry, the scaffold had raking stays to hold it in place.

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