Lime Mortar Plastering and Lath and Plaster Work

Lime Mortar plastering allows structures to breathe unlike modern sand and cement mortars, which tend to cause dampness in properties. Historic buildings are frequently constructed with relatively soft masonry units (e.g. soft brick and many types of stone), and minor movement in such buildings is quite common due to the nature of the foundations. This movement breaks the weakest part of the wall, and with Portland cement mortar this is usually the masonry. When lime mortar is used, the lime is the weaker element, and the mortar cracks in preference to the masonry. This results in much less damage, and is relatively simple to repair. Under cracking conditions, Portland cement breaks, whereas lime often produces numerous microcracks if the amount of movement is small. These microcracks recrystallise through the action of ‘free lime’ effectively self-healing the affected area.