A modern home with wood rainscreen siding

A Closer Look at RainScreen siding and avoiding Thermal Bridging

Written by Chris Nolan on Mon, Oct 31, 2011 @ 09:10 AM

In general terms a rainscreen is a sustainable design system that keeps rain (and other elements) away from the building envelope of a structure. By moving the siding material away from the building envelope (weather tight outside area of structure behind the rainscreen siding), a gap is formed between the envelope and the siding creating a "rainscreen". Of course rain is not the only element a rainscreen protects the structure from, a properly designed and built rainscreen system will shield the building envelope from snow, sleet and more. In a rainscreen system the gap between the building envelope and the exterior siding also provides a passive insulation cavity that helps save energy. Let's explore how.

cambridge-house ipe rain screen siding Seal Once cape Cod gray finish-1

How A Rainscreen Siding System Can Avoid Thermal Bridging

When it is hot outside, this buffer zone behind the rainscreen allows the hot air outside to cool off, shielding the interior of the home or structure from the thermal impact. Likewise, in colder climates or when there is cooler weather in any climate, this air space behind the rainscreen provides the same buffer zone to prevent the transmission of heat gain or loss which creates a more energy efficient design.

Illustration How Rainscreen Creates A Passive Insulation Layer

The Climate-Shield rainscreen system minimizes thermal bridging and maximizes passive energy savings

What Is Thermal Bridging In Siding?

What is thermal bridging in a rainscreen? Thermal conductivity is the ability of materials to transmit heat or cold. When materials are connected to or touch one another a thermal bridge is created. Typically, the less material that touches another material, the less transfer of heat or cold. With regards to rainscreen systems, the less material contact (thermal bridging) , the less transfer of heat or cold.

Concerns with rainscreen siding designs that use furring strips

With a typical wood siding system there is full contact of the wood siding to the building envelope. This allows the direct transmission of heat throughout 100% of the surface area. In a rainscreen system using furring strips, the furring strips become a thermal bridge. The furring strips come in contact with roughly 16% or more of the surface area of the building envelope, creating a rainscreen design which has 16% or greater thermal bridging.

Closed joint wood rain screen method with furring strips

Rainscreen Siding Without Furring Strips Reduces Thermal Bridging

The Climate-Shield™ Rainscreen System uses no furring strips. The surface area of the Climate-Shield rainscreen clip that connects the wood siding to the building envelope is less than 3 square inches. This creates a rainscreen system that has minimal thermal bridging. The Climate-Shield™ Rainscreen Clip allows design professionals a rainscreen design option to reduce thermal bridging to less than 1% of the surface area of the building envelope.

Rear view of the Ipe vertical siding and Climate-Shield rain screen system