Decision-making tool for better use of lime mortar on traditional and historic buildings

Professor Heather Viles, SOGE, and Lucie Fusade, EPSRC CDT in Science and Engineering in Arts, Heritage and Archaeology (SEAHA)

Building on both the outcomes of the DPhil research and discussions with built heritage practitioners, the project proposes to develop a pilot decision-making tool (available at https://uselimemortar.com/) to encourage and help building contractors and conservation specialists working on historic and traditional masonry to use lime mortar. Because of its breathability, permeability and low energy consumption to produce, lime is the ideal sustainable material for repair intervention on traditional masonry. However, when conserving historic buildings, repairs are still often done using inappropriate materials, such as cement, which cause more damage to the masonry. It can lead to biological growth, salt damage and humidity, which may have negative effects on the living conditions in those buildings and deteriorate valuable ancient stones and carvings. This is due to several factors: a gap between academic scientific research and contractors who make the repairs on such buildings, and the complexity of using lime, which may discourage contractors from using it. As the Historic Environment and Cultural Heritage Skills survey showed, 89% of the work on historic buildings is done by general building contractor companies. It is therefore absolutely essential to change how lime mortar is seen and make its use easier amongst conservation specialists and building contractors, but how? During the DPhil a range of lime mortar compositions was designed and validated in laboratory and test walls taking several factors into account: masonry type, conservation issues and environmental conditions of the buildings. Our project would develop a pilot easy-to-use tool, likely online, to help building contractors understand and decide on which lime mortar to use, depending on the same factors: environment, masonry type and conservation issues. This project will improve knowledge sharing between research and practice and enhance collaborations while making a significant contribution to the conservation of the built environment. The toolkit is available at https://uselimemortar.com/