Why Is My Balcony or Terrace Leaking Into the Unit Below?

The primary reason for a leaky balcony is a failure in the waterproofing membrane. This thin layer, often a rolled sheet or liquid coating, sits beneath the tiles or surface finish. Over time, this membrane can crack, lift, or wear thin from weather and foot traffic. Once compromised, water easily soaks through the concrete or wood deck and heads downward into the building's interior. This hidden moisture can travel far from the original entry point, leading to damage in unexpected areas of the structure below.

If you notice a leak, your first move is to alert the resident below and document the damage with photos. Move any furniture or rugs away from the damp area on your own balcony. If it's safe to access, check for obvious blockages in the drain. Do not attempt major repairs yourself, as improper fixes can make the problem worse and increase repair costs later on.

Repair costs vary widely, often ranging from a few hundred to several thousand dollars, depending on the leak's severity and balcony size. The final price depends on accessibility, materials needed, and the extent of hidden damage discovered during the inspection. If the leak originated from your unit, your homeowner's or condo association policy may be involved. Policies vary, and your insurer decides what is covered. Always check your policy and consult your association's bylards to understand your financial responsibilities before work begins.