Scotland has a long tradition of building with stone and lime stretching back to Roman times. A large proportion of Scotland’s buildings constructed prior to 1920 used lime mortars in both construction and finishing. From the mid Nineteenth Century the use of ordinary Portland cement (OPC) mortars became increasingly common. In the Twentieth Century it became the norm for new construction, and became increasingly used to repair traditional buildings originally built using lime mortar. This has a negative visual and practical impact, and can have a serious effect on the condition of the building. The construction industry has almost forgotten why lime was used, and is having to re-learn the skills to use it effectively. In the majority of applications lime has significant performance and visual benefits over cement mortar, particularly in relation to traditional buildings. Where modern mortars have been introduced into traditional masonry structures, the consequential rate of decay can be alarming. The purpose of the INFORM is primarily to discuss the external use of lime and cement mortars in relation to traditionally constructed buildings.