The Five Most Common Waterproofing Defects in Australian Apartments

NSW Building Commissioner reports have consistently cited waterproofing as the leading defect category in new apartment buildings. The five worst recurring failures are:

1. **Failed balcony membranes.** AS 4654 covers external above-ground waterproofing, but membrane failures behind tiles are common. Rectification means lifting tiles, redoing the membrane, and re-tiling, disruptive and expensive.

2. **Bathroom wet area defects.** AS 3740 covers internal wet areas. Failures around shower hobs, floor wastes, and tile junctions allow water into adjoining apartments below or beside the source.

3. **Planter box leaks.** Roof gardens and planter boxes are notoriously hard to waterproof. Roots, drainage failure, and inadequate detailing all contribute. Rectification often requires removing the entire planter assembly.

4. **Basement tanking failures.** Hydrostatic pressure on subgrade walls finds the smallest defect. Tanking failures usually mean ongoing water ingress into car parks and storage cages.

5. **Roof terrace defects.** Trafficable roof terraces combine the challenges of balcony membranes and planter boxes, plus pedestrian wear.

Owners corporations should commission independent inspections at the SBBIS interim and final report milestones, and not rely solely on the developer's certification.