A home will naturally settle a little during the first few months after it has been built. When the home settles, the walls move slightly. This puts stress on the drywall, which will develop very small, hairline cracks. These cracks can run vertically or horizontally and often appear along drywall seams. Serious home settling may indicate a foundation problem, but more serious settlement normally shows large cracks through walls, concrete and even wood or brick walls.
Homes that are composed of wood will move slightly as the seasons change. Wood swells during the summer and shrinks slightly during the winter. This can cause hairline cracks to develop in the drywall. Using flexible drywall mud will help prevent this from happening every year.
Homes located in dry climates are more susceptible to hairline cracks in drywall. This happens when the inside of the home has a very low relative humidity that causes the drywall mud to dry out and begin to crack. This can also happen if you use a dehumidifier to help prevent mold or mildew. Adjust your home's relative humidity with the help of a humidifier or by readjusting your dehumidifier.
No matter how well you care for your drywall, it will age and naturally develop small hairline cracks. Some homeowners embrace this aged look while others cover it with drywall patches or more drywall mud.