Here is a good example of how a common oversite can cost consumers money. In this tutorial I am going to explain why this scupper failed. I am also going to show you how to do a basic repair that will stop the leak . And finally I’m going to show you the damage caused by neglect.
In the picture below you will see a failed scupper. The reason this scupper failed was due to the roofer not tearing out the old roofing from inside and around the scupper, before applying the new roofing material. Common practice for overlaying an old roof with a new roof is to what they call “divorce” the old roofing from around scuppers, pipes and other penetrations. The reason they do this is because these are weak areas and are often the source for leaks.
As you can see where the arrows are pointing are places the old mastic has dried out and seperated from the scupper. Had all of that old material been removed prior to the new roof installation this would have never happened.
Ok now that we can see where our leak is, how do I fix it? Go get a couple tubes of urethane caulking and a caulking gun apply the caulking in all the cracks and tool it with a piece of cardboard or putty knife. You can then apply some elastomeric roof coating over the top of that And the repair is finished.
This kind of fix is easy to do yourself. This type of repair is considered a permenent fix. However if your roof is under warranty call your roofing contractor and have him tear out the old material and redo it. If this happened at one scupper chances are all of the scuppers are the same way and need to be corrected.
Below is a picture of the damage this leaking scupper caused.