A cracked ceiling.
Ceiling cracks happen naturally over time as a result of many factors. The older the structure, the more likely it is that stress, moisture and temperature will cause cracks to form. Several other factors, however, can accelerate the wear and tear effect. Poor workmanship is the most common cause of initial cracks in a ceiling, especially if an inferior technique was involved in the construction of the ceiling. Other external factors such as accidents and forces of nature can also lead to the formation of cracks.
Cracks in the foundation can be a sign of structural damage.
All materials used in construction wear out over time. Gypsum, wood and other materials crack under the stress and pressure built up over time. This is especially true if the ceiling in question has another floor or attic above it. A large amount of force coming from the upper floor can be enough to cause the lower floor ceiling to crack. As a general rule of thumb, the thicker the floor, the stronger the lower floor ceiling and the less likely it is to crack.
Homes in countries that experience seasonal monsoons often experience ceiling stress.
Fluctuations in temperature and humidity can also cause the ceiling to crack. Materials expand when wet or hot and contract when cold. If changes in heat or temperature happen sporadically, as in monsoon seasons in tropical climates, this can lead to undue internal stress on the ceiling materials, causing the ceiling to crack. In most cases, the crack is formed in the thinnest layer of paint on the ceiling surface, although cracks in the plaster itself are also possible.
Pressure, temperature and humidity can have a more significant effect if the ceiling is built with a poor finish. For example, cracks in the ceiling are more likely to form if the builder forgets to put an additional layer of drywall compound in the areas where the wall meets the ceiling. Without the support for the additional compound, cracks can form due to poor adhesion. This is also true if low quality building materials are used in the construction. Providing an inadequate foundation for the building will also lead to cracks in the ceiling as much of the internal weight will be supported by the walls and ceilings.
In extreme cases, cracks in the ceiling can form immediately. This usually happens when the pipe has suddenly burst and put a lot of pressure on the ceiling or walls. Earthquakes of a large enough magnitude can also cause the weight of the building to shift and form a crack in the roof. Any sudden and powerful impact, such as a physical blow, can weaken the structural integrity of the ceiling and cause it to crack.