Cracks occur as buildings age. Temperature changes and weather conditions make them grow. They can be classified as structural or non-structural.
Structural Cracks:
Structural cracks, that are usually found in the load-bearing parts of the construction like beams and columns, are serious. They are caused by movements of the foundation, shrinking of masonry as it dries or heat-related roof shifting. They form in straight vertical or horizontal lines and or stepped diagonal lines. These cracks should be taken care of by specialists.
Non-structural cracks:
Non-structural cracks refer to cracks in the plaster of interior or exterior walls. They are mostly caused by reactions within plaster compounds and building materials, and external forces like temperature changes, environmental factors etc. They can also be caused by use of poor materials and inferior labour. They are usually haphazard and not very wide, and are found on the flat portions of the wall and not on the load bearing areas. They can be effectively treated using crack filling compounds. Make sure to fill the crack till the wall is level.