Author: J. Miller (Ramboll)
1 December 2015
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J. Miller (Ramboll)
The greatest threats to the structural integrity of timber are from attack by rot and insect; therefore, in the damp British Isles, those working in conservation will often need to reach for the sketchpad to record and re-detail areas damaged by the effects of moisture.
Interventions to historic timberwork are also necessary when a building is converted. This happens, for example, when floor joists are reframed or loading is assessed for a new use. While philosophically this is different to a simple repair, it nevertheless requires similar skillsets to achieve the best, most sensitive results.
This article looks briefly at these matters, first from the aspect of conservation philosophy and material choice to establish some ground rules, and then by showing some of the details typically in use in the UK today. In order to focus on these, it does not consider survey and diagnosis.
The Timber Engineering Notebook series concludes by examining the use of glued-in rods for timber connections. The increased use of manufactured timber, such as glued laminated timber (glulam) and laminated veneer lumber (LVL), with improved mechanical properties and the ability to produce cross-sections of almost unlimited size,has driven the timber engineering industry to come up with improved connection systems. Glued-in rods and plates have been used in the UK as a method of connecting timber since the 1970s. They offer the possibility of creating concealed connections that are capable of transferring large forces and moments with minimal slip due to their high stiffness.
Our built heritage is a finite resource stretching back thousands of years. Protecting and conserving this heritage is a challenge requiring knowledge, skills and experience, together with an ability to bring practical engineering judgement and often creative and imaginative solutions. This paper sets out the challenges faced by engineers and some of the approaches taken in the appraisal and protection of ruins.
In this article, issues associated with the scaffolding of historic structures are briefly explored and illustrated through four case studies. These are projects that crossed the author's desk, as a consulting engineer specialising in the conservation of historic structures, within a few months of each other. They explore some of the constraints imposed by 'historic fabric' and other factors, the compromises made, and the solutions reached.