This project is relocating and rebuilding the Crannog Centre on the opposite shore of Loch Tay from the original site. This follows the loss of the original recreated Crannog structure to a devastating fire in 2021.
The new proposals include constructing a new Crannog structure – a prehistoric dwelling common throughout Scotland and Ireland, constructed on lochsides. This new site replaces the one lost in 2021, with plans to construct up to three in total. There are also a series of land based Iron Age structures that have now been constructed. These structures form a recreation of an Iron Age Village. There is also a new modular visitor centre constructed using Structural Insulated Panels (SIPs) that has been designed by SIPs specialists.
Narro’s primary role has been as consulting engineers for the Crannog and Iron Age Village structures. However, we have actively participated in all aspects of the project. While the Crannog itself is still under construction, many of the Iron Age Village structures are now complete. These structures have all utilised historically accurate methods of construction and materials appropriate to the Iron Age, based on archaeological evidence. Throughout the project, we have primarily utilised locally sourced, natural, round timber as the construction materials. This is untreated and unprocessed and so is geometrically and qualitatively variable.
All structural connections were formed with traditional timber carpentry techniques, utilising hand-crafted timber pegs/dowels and hemp rope lashing. This presented an increased degree of uncertainty and various engineering challenges, primarily due to being unable to directly apply conventional engineering design procedures. Instead, the engineering approach for these structures has been more pragmatic in nature and largely derived from first principles. Moreover, the structures necessitated a Building Warrant, thus SER Certification, requiring Narro to provide substantive evidence that the structures would comply with modern building standards.
The SCC construction team, possessing the expert knowledge and experience in the construction methods and techniques involved, built the Iron Age structures. They had a significant role in developing the design of these structures and part of their aim was to showcase as many different construction techniques as possible. This meant all structures had a unique structural strategy to some degree.
Design of the timber elements was based on the species of timber and approximate/average diameter of the round section. An example of this was proposing locally sourced larch as the primary structural timber, subject to availability. According to the British Standard of Structural Timber Strength classes (BS EN 1912:2012), UK sourced larch can either fall into C16 or C24 strength grades. For design purposes, and to reduce uncertainty, we assumed the lower strength.
