Why does my roof leak only during some storms?
Intermittent leaks usually point to details that only fail under particular conditions: an outlet that backs up in very heavy rain, a low upturn at a door that floods when water ponds, or wind-driven rain entering a parapet coping or façade joint above the roof line. Singapore's Sumatra squalls bring gusts of 40 to 80 km/h, so record the date, time and wind direction of each leak to help the investigator.
From the RRD Field Guide, checked against the sources cited in Flat Roof and Wet-Area Waterproofing in Singapore: Membranes, Ponding, Leak Tracing and Repair. General information, not advice for your project.
The fuller picture
Most flat-roof and bathroom leaks in Singapore come from failed membrane details, not the open field: upturns, outlets, penetrations and laps. Diagnose before repairing, using a controlled flood (ponding) test, moisture mapping and inspection. The code of practice is SS 637:2018. In strata buildings the roof membrane is common property, so the MCST repairs it.
More questions on this topic
- How long should a waterproofing ponding test last?
- Which is better: torch-on, liquid or cementitious waterproofing?
- Who pays for a roof leak into a top-floor condo unit?
- Can I just coat over my old roof membrane?
- What does a waterproofing warranty usually cover?
- Do I need BCA approval to redo roof waterproofing?