A well-constructed masonry building may seem completely stable and unmoving. However, masonry buildings, like all buildings, are not motionless. Unseen to the eye, they expand and contract with changes in temperature, moisture content, and stress; they move and are alternately or simultaneously stressed and relieved as a result of wind and weight loads, foundation settlement, and vibration. All these forces, and more, continuously act on a building. If details are not specified to accommodate these movements, cracked masonry can result. Troubleshooting masonry cracks is not always easy. Frequently, the problem logically can be attributed to several causes. At other times, there may seem to be no apparent cause. A list of common cracks and their likely causes has been provided.