Why Balconies Leak
Balconies leak for several reasons: failed or absent waterproofing membrane, cracked tiles allowing water ingress, failed sealant at the junction between balcony and wall/door frame, blocked or failed drainage, or corroded structural elements. Identifying the source of the leak before starting work is critical — patching tiles on a structurally failed balcony is money wasted.
Structural Assessment First
Engage a structural engineer to assess any balcony showing signs of distress: concrete spalling (chunks falling off the soffit below), visible rusting reinforcement, significant cracking, or deflection (sagging). These signs indicate carbonation or chloride-induced corrosion of reinforcing steel — a structural issue, not just a cosmetic one.
⚠️ Watch out: Never walk on a structurally compromised balcony. Corrosion of reinforcing can cause sudden, without-warning failure. If in doubt, fence it off and get a structural assessment.
The Restoration Process
- 1 Strip all existing tiles and failed membrane completely — partial repairs rarely last
- 2 Repair concrete: remove spalled concrete, treat exposed steel with rust inhibitor, patch with polymer-modified repair mortar
- 3 Apply new waterproofing membrane to AS/NZS 4654 (external membrane standard)
- 4 Lay new tiles with minimum 2% fall to drain (often forgotten in original construction)
- 5 Replace balustrades if they show corrosion at fixings — these are structural elements
Balustrade Safety
Balustrade height must be 1000mm for residential balconies (1200mm if more than 4m above ground in some states). Balustrades must not have horizontal rails that could be climbed. Post fixings through concrete must be checked for corrosion — corroded fixing bolts can fail under impact loads. Have an engineer certify any balustrade structural repair.
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