It Almost Never Leaks in the Field

A leak is reported, somebody goes up, walks the field, finds nothing obvious and applies coating to a suspect area. The actual entry point is a pipe boot, a drain, a parapet coping or a piece of equipment that was set on the roof after it was built — and none of those is in the field anybody walked.

A commercial low-slope roof here is not primarily fighting rain. It is fighting ultraviolet exposure, thermal cycling and uplift, all year, on a surface that spends much of the day significantly hotter than the air. Membranes age faster in this climate than the same product would elsewhere, and the failure is gradual — a membrane does not stop working, it becomes less tolerant of the next event.

Then the events arrive. Uplift finds inadequate attachment at perimeters and corners, which is where nearly all wind damage begins. Ponding after heavy rain adds load and accelerates deterioration wherever drainage is poor. And penetrations — every vent, curb, drain and mount — are individually small and collectively the most common source of leaks on any roof we investigate.

1. 01Investigate the actual entry point before proposing a repair.
2. 02Detail penetrations and terminations properly, not with mastic.
3. 03Correct ponding where drainage is inadequate.
4. 04Rebuild parapets and copings where they have failed.
5. 05Document for the owner and for any warranty.

Ask what was installed on the roof after it was built. Satellite dishes, condensers and cable trays fixed directly through a membrane are one of the most common leak sources on a commercial roof, and they never appear on any drawing.

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