How Does a Wood Rain Screen Work?

All wood siding looks naturally beautiful from the outside. It’s the ‘what’s going on behind the siding part’ that varies using different types of installation techniques. It is now becoming widely recognized that wood rain screen systems provide additional layers of protection that allow a home or building to breathe and shed moisture properly. The wall cavity (gap behind the siding) is the key to best performance.

Back in the day, wood siding was almost always nailed directly to the exterior sheathing of a structure. With no back ventilation behind the siding, the problem that typically arises is trapped moisture behind the siding, with nowhere to go, which fosters mold growth and the mold eventually rots the wood, creating health concerns and additional expenses. It also reduces the functional lifetime of a building and dramatically increases maintenance and life cycle costs.

Over the past ten or so years, several companies have developed ‘rain screen’ products that work reasonably well to create a wall cavity. Just because you can't see it, doesn't mean it's not working for you. But please be aware that some systems work much better than others. The only factor that is common to all wood rain screens is that there is an air space behind the siding. From there, performance of the various wood rain screens is based on a number of very different factors:

How Well Does a Rain Screen Work:

1. Is there a wall cavity (air space) behind the siding? If so, it can be called a ‘rain screen’.

2. Is there back ventilation? If not, how will the trapped moisture escape?

3. Is it a closed joint rain screen? If so, how will moisture escape from the wall cavity?

4. Is it an open joint rain screen? If so, how will bulk water escape from the wall cavity?

5. Are wood furring strips required? If so, how will they dry out…and what happens if/when they rot?

6. Is it a pressure equalized rain screen? If so, this will perform more effectively in high wind and foul weather conditions, and will dry out rapidly from rain or moisture.

Of all the available wood rain screen options, the Climate-Shield® Rain Screen System™ is the only one that is patented, back-ventilated, open joint, pressure equalized and requires no wood furring strips. In wet conditions outside or moisture conditions from inside, Climate-Shield is regarded as the most effective wood rain screen system. Here’s how it works:

As you can see in the diagram above, the entire rain screen system is designed for maximum performance:

• Effective and unobstructed route for moisture from inside the structure to escape (without using furring strips)

• Minimal penetration of bulk water from wind driven rain or other sources (specially designed open joint profile)

• Easy drainage of bulk water from the wall cavity when it does occur (3/4" wall cavity and specially designed starter rail)

• Rapid elimination of moisture from the wall cavity (pressure equalized design)

If you are looking for natural wood siding with high performance and exceptional long-lasting beauty, consider the Climate-Shield rain screen system for your design and construction needs...not just another pretty face.

Please visit our website for more information about rain screen design, Climate-Shield and wood siding options.

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