State of Iowa Judical Branch Building, Des Moines, Iowa Architect: DLR Group

Building forensics have proven that an exterior sealed building will eventually break down due to thermal cycles. When this exterior seal breaks down, the negative pressure then creates a point of suction where water is pulled into the wall.

Rain screen technology eliminates the dependence on an exterior seal because a backup wall has now taken on the role of the air and weather barrier. By utilizing a backup wall as an air barrier, insulation is then located on the outside of this barrier and the veneer has open joints. The air that enters the system keeps the insulation dry and prevents moisture from being trapped therefore, the dew point is no longer occurring inside the wall cavity. As a result of the open joints, pressure equalization prevents moisture from being pulled into the wall, allowing the system to ventilate itself.

Rain screen technology uses all the components of a traditional wall but rearranges their order of placement.