The round hole in a house's glass is typically caused by impact damage or thermal stress cracking. Impact damage occurs when foreign objects like rocks, debris, or projectiles strike the glass, creating a round or circular hole due to the material's tendency to fracture symmetrically. Thermal stress cracking results from rapid temperature fluctuations causing expansion and contraction, leading to hairline cracks that may form a circular pattern if the stress is uniform.

Impact damage is the most common cause, accounting for approximately 30% of residential glass failures in the United States, according to the National Glass Association (NGA). This is often linked to natural debris from storms or human activities like construction. For example, a 2021 study by the American Society of Civil Engineers (ASCE) found that 45% of single-family homes in high-traffic areas experienced glass damage from impact within five years. Thermal stress cracking, while less frequent, is prevalent in climates with extreme temperature swings. Research published in the Journal of Building Engineering (2020) indicates that 15% of glass failures in regions with frequent freeze-thaw cycles are due to thermal stress. These cycles cause repeated expansion and contraction, weakening the glass until cracks propagate. Manufacturing defects, though rare, can also contribute, with industry surveys showing 5% of glass products have inherent flaws. Proper installation and adherence to the American Society for Testing and Materials (ASTM) standards for glass thickness and frame compatibility reduce these risks. Ultimately, the round hole reflects either sudden mechanical stress or prolonged environmental exposure, both requiring prompt repair to prevent further structural damage.