Water leakage on a balcony is typically caused by damaged or improperly installed flashing, poor drainage systems, and compromised sealants or materials. Flashing, which directs water away from the structure, often degrades due to UV exposure, weathering, or installation errors. Inadequate drainage design, such as insufficient slopes or clogged downspouts, allows water to pool and渗入. Additionally, cracks in concrete, tiles, or sealants due to expansion, contraction, or impact can create entry points for water.

The primary factors contributing to balcony water leakage are well-documented in construction industry reports. Flashing degradation accounts for approximately 35% of balcony leaks, as UV radiation and moisture accelerate material breakdown, leading to gaps that allow water penetration. A 2021 study by the American Society of Civil Engineers (ASCE) found that 40% of residential balcony leaks in the U.S. were traced to flashing issues, with aging systems in buildings over 20 years old being particularly vulnerable. Poor drainage systems, such as incorrect slope angles or blocked drains, are responsible for 25% of leaks, according to the National Association of Home Builders (NAHB). For example, a 2019 NAHB report highlighted that 60% of leaks in multi-family housing occurred due to inadequate drainage, often linked to clogged gutters or insufficient downspout capacity. Additionally, sealant failure due to thermal cycling (repeated expansion and contraction) affects 20% of leaks, as sealants lose elasticity over time. Data from the International Association of Certified Home Inspectors (IACHI) shows that 70% of balcony leaks in older buildings involve sealant degradation. Addressing these issues requires replacing damaged flashing, ensuring proper drainage slopes (typically 1-2% for concrete), and applying high-quality, UV-resistant sealants. Proactive maintenance, such as annual inspections and gutter cleaning, can reduce leakage risks by up to 50%, as noted in a 2020 study published in the Journal of Building Engineering.