Avoiding lime failures

Lime mortar has been used in the construction of traditional buildings in Scotland for centuries. Its use began to diminish from the mid-19th century as mass-produced Portland cements became more widely available. A century later its use as the primary binder in mortar had all but ceased and, within a generation or two, most of the skills and knowledge needed to use lime successfully were lost. Since the lime revival of the late 20th century, and following much research, the benefits of using lime in traditional masonry are becoming increasingly understood. Lime, compared with modern materials such as cement, is much more compatible with the surrounding fabric, especially its ability to allow buildings to ‘breathe’. Despite this revival, however, there is still a belief held by many that lime mortars are difficult to use and susceptible to failure. This paper explains that ‘lime failures’ are much more likely to be caused by failures of workmanship, specification, building detailing and maintenance than the actual material itself, and argues that, provided these largely avoidable factors are considered, there is no reason why any appropriately specified and well-applied lime work should fail on a well-detailed and regularly maintained building.