Water leakage on a balcony typically occurs due to compromised waterproofing systems, structural damage, or improper drainage. Common causes include cracked or degraded waterproof membranes, faulty flashing around edges, clogged drainage systems, or gaps in balcony enclosures. These issues allow water to渗透 into the structure, leading to interior damage and mold growth.

The primary factor is waterproofing failures, which account for 15-20% of balcony leaks according to the International Association of Certified Home Inspectors (IAC4). Over time, materials like rubber seals and bitumen-based membranes degrade due to UV exposure, temperature fluctuations, and foot traffic, reducing their ability to prevent water infiltration. For example, a 2021 study by the National Association of Home Builders (NAHB) found that 30% of leaks in multi-family buildings stemmed from aging waterproofing systems. Structural damage, such as cracks in concrete slabs or weakened fasteners, exacerbates the problem. The NAHB also reports that 25% of balcony leaks involve compromised flashing, which directs water away from walls and joints. Additionally, poor drainage design—such as blocked downspouts or incorrect slope angles—collects water on the balcony surface, increasing pressure on waterproofing layers. Mitigation requires inspecting and replacing damaged materials, ensuring proper drainage, and applying sealants to gaps. Proactive maintenance can reduce leakage risks by up to 40%, as noted in a 2022 report by the American Society of Civil Engineers (ASCE). Addressing these issues promptly prevents costly repairs and ensures occupant safety.