Architectural Detailing - Edward Allen, Patrick Rand
We defined in leakage that three conditions are necessary for water leakage to occur. Water must be present, there must be a hole in the assembly and there must be a force to push the water through. One force that is always present is gravity, fortunately it can be used to our advantage. Sloping and vertical surfaces can be clad material pieces where the upper surface extends over the lower surface. This organization of materials is called an overlap and is a very effective means of keeping water out, gravity wants to pull water downward. The lower the slope of a surface the greater the materials must overlap.