Double trouble

Other than what insurance companies call an “Act of God”, there are two main reasons a roof can start to leak. Either through poor/negligent workmanship or because of failed materials. It’s rare you get a leak that is caused by both. Such was the case today in Vancouver. It first started out as a leak around a scupper drain on a roof top deck. This is a common deficiency in roof top decks using through-wall scuppers as a drainage means. The membrane loses it’s bond with the copper and a leak begins. I have several reasons to call this deficiency a workmanship issue…. but in this case membrane separation wasn’t the problem. The first thing I found was a round hole in the base of the scupper. That’s odd I thought. It’s just too round. Further investigation found copper erosion and fatigue at a different location. The scupper drain had to be replaced. When I removed the old scupper I figured it out. The evidence to this mystery was in front of me and it was easy to solve. A careless worker had drilled a hole in the scupper from underneath. Once this was realized someone patched the hole, on the roof level, with a roofer’s mastic…. which was destined to fail. Elsewhere on the scupper the fatigue and erosion was quite serious. So here we have it – “Double Trouble”. Workmanship and materials both failing in the same location. Maybe I should go buy a lottery ticket.