Thermal Bridging and Energy Efficiency in Rainscreen Siding

By Steve Getsiv, 05/03/19

Why You Should Install Rainscreen Siding on Your Building

Rainscreen siding systems have huge benefits for your home or building. They make your building more aesthetically pleasing while also saving on overall energy costs. Initially, rainscreen systems are more expensive; and making the right choices in your rainscreen siding system requires a deeper understanding of these energy saving properties before making the initial investment.

What is Rainscreen Siding?

Rainscreen siding systems refer to the style of installation and fastening of the siding material to the structure of your building. Moving the siding away from the building creates a gap that is called the "rainscreen". Rainscreens are designed to help keep the rain and other elements away from the building structure. Most importantly, a rainscreen creates an exterior siding system that acts as a passive insulation cavity which saves energy.

The air gap in a rainscreen siding system is between the outermost layer of siding and the building structure itself. This air gap, which generally measures around 3/4", greatly enhances the thermal insulation as well as creating a stable moisture environment for the outer layer of siding material. This is especially important when using hardwood or softwood as siding material since wood can be prone to cupping, warping, swelling and shrinkage with changes in humidity.

When looking at the finished structure, the air gaps are completely invisible. These air gaps matter because they protect the structure underneath the outer layer of siding and keeps this outer layer more stable. A properly installed rainscreen system will also allow for very small ventilation gaps between the siding boards themselves, generally in the range of 1/32" to 1/16".

What is Thermal Bridging and Insulation?

When it is hot outside, the rainscreen acts as a buffer zone which makes the hot air outside cool off, protecting the home from thermal impact. The same effect works in cold weather. The air space in the rainscreen creates a buffer zone that tempers both heat gain and heat loss. This helps to insulate your home or building during the winter.

Thermal conductivity is the ability of materials to transmit heat or cold. When materials touch one another, this creates a thermal bridge. The best designed rainscreen systems have as little thermal conductivity as possible to minimize the thermal bridging of energy between the structure and the outer layer of siding. Using small aluminum clips with a ¾" standoff creates a much smaller transfer of heat or cold when compared with using full length furring strips running perpendicular to the exterior siding.

Installing a rainscreen system without stand-off clips, by using furring strips instead, you will lose much of the thermal insulation benefits as well as inhibiting the free-flowing ventilation characteristics of the superior rainscreen clip system. The thermally conductive connection points of aluminum clips used every 16" offers a ten times improvement in reducing thermal bridging when compared with conventional furring strips.

Why It Matters

When considering if you want to use rainscreen siding, it is important to not only think about the aesthetics of the structure's appearance but also the amount of energy that you will use during the lifetime of the structure. Rainscreen wood siding conserves more energy than conventional siding because of the minimal thermal bridging and insulation; and when installed with aluminum clips with a built-in standoff, the energy saving benefits are maximized because the thermal bridging is minimized.

It is important to not just think of rainscreen siding systems as an aesthetic upgrade, but as an environmentally sustainable and energy efficient option as well.

By Steve Getsiv, 05/03/19

"I completely agree with the added benefit of rain screen providing thermal break. I came across this article researching this very topic. Thanks for posting."

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