Balcony Waterproofing Failure

• Identify all areas of water ingress to the soffit or internal ceiling below the balcony.
• Map membrane condition across the balcony field, upturns, junctions and penetrations.
• Assess falls and drainage to confirm water is directing away from the building and not ponding.
• Inspect all penetrations including balustrade posts, pipes and anchors for failed or absent sealing.
• Check perimeter upturns for height compliance and continuity with the wall or door threshold detail.
• Flood test or moisture scan to confirm leak location and the extent of water-affected substrate.
• Inspect the substrate beneath any tiled finish for soundness using hammer tap testing.
• Assess structural condition of the concrete slab or substrate for deterioration caused by prolonged moisture.

Typical Repair Methodology

The repair scope must be confirmed by a waterproofing consultant or engineer. The sequence below reflects a typical full-replacement methodology for balcony waterproofing failure.

1. 01.Confirm the repair scope with the engineer or waterproofing consultant, including substrate condition and system selection.
2. 02.Isolate the work area and protect adjacent finishes and structure from damage during removal works.
3. 03.Remove all tiles, adhesive beds, screeds and existing membrane system to expose the concrete substrate.
4. 04.Remove balustrade posts and any embedded penetrations as required to allow full membrane continuity.
5. 05.Assess the exposed substrate for deterioration, spalling or reinforcement corrosion and repair as directed.
6. 06.Prepare the concrete substrate by grinding or scarifying to remove all laitance, adhesive residue and contamination.
7. 07.Form or rebuild falls where insufficient — minimum 1:100 fall to drains is required under AS 3740.
8. 08.Inspect and repair all drains, ensuring they are flush with the finished membrane level and correctly positioned.
9. 09.Prime the prepared substrate with the approved primer compatible with the selected waterproofing system.
10. 10.Install the approved waterproofing membrane system to the full field area, upturns and all junctions in accordance with AS 3740.
11. 11.Ensure upturns extend a minimum 150 mm above the finished surface level at all wall and door threshold junctions.
12. 12.Form coved transitions at all angle changes — no sharp 90-degree intersections permitted.
13. 13.Install pre-formed or site-formed membrane collars at all penetrations including balustrade post sleeves.
14. 14.Carry out a flood test in accordance with AS 3740 to confirm waterproofing integrity prior to tiling.
15. 15.Install tile bed, tiles and approved grout system over the confirmed watertight membrane.
16. 16.Record QA documentation including flood test results, product batch numbers, application thicknesses and photographs.

Before / After Repair

Typical balcony waterproofing condition before and after full membrane replacement and tiling works.