Like most constructions, ceilings are subject to change and wear. It is quite normal to see and hear about cracked ceilings, especially after a seasonal change. While cracked ceilings might sometimes be serious, usually they are only surface-based and can be mended easily enough.
Commonly cracks appear after a weather bout of heat or cold. Both extremes can lead to undesirable ceiling motion, either in the form of an expansion or contraction. Once set, a ceiling does not have the luxury to move much. Excessive heat or cold however, will either expand or contract it, leading to ceiling cracks. Once the weather settles down, the crack can be filled up with plaster of Paris and reclaimed. Seasonal cracks are not dangerous, and are considered part and parcel in civil works.
Wider cracks can indicate structural damage though. Cracks that start at the ceiling and touch any of the walls are clear indicators of serious ceiling damage. The most common cause of these cracks is the settling of the house. Houses built in earthquake prone areas will often exhibit these cracks. A â€˜dip’ in the ceiling might indicate that the ceiling is not supported well, or one of the supports has eroded away. This would require a structural overhaul, and the ceiling would have to be made anew.
The rule here is simple: the width of the crack defines the seriousness. Most cracks are surface-based, and as discussed previously are of minimal concern. Weather changes along with heavy rainfall, are the primary causes of surface cracking. Structural damage leads to wider, more accentuated cracks. These are dangerous, and usually occur in earthquake prone, soft ground areas.