What is the difference between a “water management system” and a “water barrier system”?

Most stucco systems are exposed at one time or another to large volumes of water in the form of wind driven rains. Because of this any wall system must have a ‘strategy’ for protecting the structure from water damage. The two most common approaches are water barrier systems and water management systems:

The strategy behind water barrier systems is to never let any water inside the building assembly. In other words, when built right the water never penetrates past the outer surface of the wall. This is difficult but possible to do. However, once there is a failure it can easily become catastrophic because large volumes of water can be trapped for an extended time before someone knows it, resulting in rot, mold, and expensive repairs.

The predominant strategy used now are ‘water management’ systems. These systems make the assumption that water will eventually work its way past the outer surface of the wall – but when it does a system of flashings, weather barriers, and metal or plastic weep screeds will direct water back to the outside of the structure.

All portland cement, hard-coat systems – either one coat or three coat – are built based on the ‘water management’ strategy.

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