What is the purpose of expansion joints in construction?

The purpose of expansion joints in construction is to accommodate movement due to moisture expansion, temperature changes, and other factors that can cause materials to expand and contract. As materials heat up, they tend to expand, and when they cool down, they contract. Without these joints, this movement could lead to stress on structural elements, causing cracks, buckling, or other forms of damage. By incorporating expansion joints, engineers and architects can effectively manage these changes, ensuring that buildings and structures maintain their integrity over time.

The other options, while relevant to various aspects of construction, do not accurately describe the primary function of expansion joints. For instance, while improving drainage is important in many construction contexts, it is not the main purpose of expansion joints. Similarly, expansion joints are not primarily designed for aesthetic appeal, nor are they structured for supporting loads, as their main role is specifically related to accommodating movement within materials.