"Fish mouth"

This deficiency is called "fish mouth". It is very popular and in the case of bitumic and multilayer roofing usually does not represent the threat of leakage. In case of one-layer and welded roofing the threat of leakage exists. In order to find the origin of leakage below, one has to eliminate weak points like that because water can travel horizontally long distances before it reveals. When all other means have been exploited, the suspected roofing areas have to be isolated and flooded.