Finally, there's condensation. When warm air hits cold air or a cold surface some of the water vapor held in the air releases as liquid. The temperature at which this happens is called the dew point. Those of us in the Northeast are all too familiar with this concept. When we walk outside after a steamy summer night and everything is dripping wet, we know we hit the dew point. This happens inside our wall cavities as well. The issue is somewhat compounded by the fact that we like the insides of our homes to be the opposite of what’s going on outside, warm in the winter, cool in the summer. Without a way for this moisture to drain and evaporate, we have problems.
How Does a Rainscreen Help?
The reality is, there is nothing we can do to eliminate these outside forces or to curb the nature of water. What we can do is manage it. This is where a rainscreen comes into play. The first line of defense is the screen itself, that is the wood siding. It is a physical barrier against the elements. The second is the airspace behind the siding, and this is the key.
The airspace breaks the capillary action. By separating the cladding from the building there is nowhere for the water to go once it reaches the backside of the siding material. Bear in mind, there must be a minimum 3/8 inch space because water can also bridge small air gaps.
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Secondly, a properly ventilated, open joint rainscreen creates a pressure equalized system which will negate the push and pull forces of wind and temperature. The airspace also creates a thermal break so that a warm building is separated from the cold cladding keeping condensation away from the building. Finally, any moisture that finds its way into the wall cavity has the space and air flow to dry out, preventing rot and mold.
Hey, What About the Building Wrap?
Protect your investment. The final line of defense is the house wrap, also known as a weather resistive barrier (WRB) or air and water barrier (AWB). Selecting the right WRB for your home or building is a critical decision. There are lots of high performance WRB’s on the market today, and many are far better than the original ones that were introduced in the early ‘90’s. They protect your home longer and are absolutely worth the slightly higher cost. Choose the one that works best for your project needs.
A common misconception is that because you are installing a rainscreen, that building wraps are not as necessary anymore. Nothing can be further from the truth. A rainscreen is the first line of defense. The best rainscreen systems are often ‘open joint’ systems. They allow water in – and let it out. That’s why WRB’s are more important than ever. So, as the final line of defense, a properly installed WRB is crucial. Don’t leave any gaps and protect all seams and flashed areas.
The Climate Shield Wood Siding System is designed to work with and help address all of these issues. Climate Shield rainscreen clips, starter rails and other components are made of marine grade extruded aluminum and are built tough, able to withstand winds up to 200 mph, making them suitable for any environment. Because this system allows airflow across the entire wall, unlike wooden furring strips, the Climate Shield system is truly pressure equalized. When used with attachment channels or Z-Girts, there's a solution for any situation, commercial or residential.