Diagnosing and Fixing Leaking Balconies

About this course.

Balconies leak because they combine everything that makes waterproofing hard — full exposure to weather, constant movement, reliance on falls and drainage, and a critical threshold right at habitable space — with the fact that the real barrier (the membrane) is usually hidden under tiles and can fail invisibly for years before the damage shows. Leaking balconies are among the most common and most disputed defects in Australian buildings, particularly in apartments, and the direct causes almost always come down to a short list: a failed or absent membrane, inadequate or reversed falls, blocked or missing drainage, cracked or deteriorated tiles and grout, and failures at the threshold and at junctions. Understanding this list is the starting point for diagnosis, because a lasting fix must address the actual cause, not just the symptom.

The first and most fundamental cause is a failed or absent waterproofing membrane. The membrane beneath the tiles is the real barrier; tiles and grout are a wearing finish and are porous. If the membrane was never installed (it does happen), was poorly installed (thin, discontinuous, badly detailed), or has failed over time (degraded, cracked at a moving junction, damaged), water passing through the porous tiles and grout reaches the substrate and structure and leaks. A membrane failure is the most serious cause because it usually cannot be fixed without removing the finish.