The most common causes for damage in masonry are settlement of foundations, water penetration, wind erosion and air pollution. Ma jor foundation settlement is a problem for a structural or geotechnical engineer, but it is useful to determine if the movement is active or has been stable for many years. Some cracks may date from the early years of a building's lifetime and not pose an ongoing problem. In the lower part of the wall, the bricks have actually been displaced, and rebuilding is required. The brickwork in the upper part can be repointed.
Water is most often the cause of active and serious damage to masonry.
One source is rain or snow, which can usually be traced to roof leaks, malfunctioning gutters and rainwater leaders. Rising damp can be controlled by improvements to the perimeter drain system, control of surface water close to the building, or by installation of a damp-proof course within the wall, a complicated procedure. Wind erosion can occur with soft brick, stone and mortar in exposed locations. Similar damage is caused by sandblasting, which is not an acceptable treatment for masonry. Chemical stripping is generally the best method for paint removal.