Rainscreens is a building practice that is not commonly used on residential construction, at least not in my part of the world. It is fairly common building practice in commercial buildings.

It is a pretty basic design concept. Your outer finish or cladding is in essence decorative and constructed to shed water, block the wind and protect the building wrap.You create an airspace behind the cladding to remove an moisture that makes it past the cladding and then can weep out the bottom or just dry from ventilation/evaporative drying.The 4 main components are, cladding, airspace, drainage plan and weep screen/holes.

Here is a home that was has a rain screen design. Using both wood and cement fiber panels.

When installed correctly it will create ventilation that will improve drying in the cavity, add life to wall components and provides continuous drainage. No exterior cladding is perfect so these systems will add that additional layer of protection. We still need flashings to be performed correctly at all penetrations.

These system will be more forgiving because they do not rely on a perfect cladding barrier. If done correctly they are relatively inexpensive and very durable. As long as the drainage and weather barrier is properly performed the system should function very well.

This leads me to think why do we not see this more often in residential construction? In some areas this may be a requirement but definitely not here. There is an additional cost in installation, which we know is the main driver for almost all decisions but if the durability of the system is greatly increased wouldn’t this offset some of the initial cost.  

From the  NAHB “The few cents per square foot spent on a rainscreen offers exceptional value to design professionals seeking liability protection, builders wanting to avoid callbacks, and homeowners looking for comfort.”

Here is a good link on rain control from building science corp.

http://www.buildingscience.com/documents/digests/bsd-013-rain-control-in-buildings

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