Specifying a ventilated rain-screen installation is an important decision. When siding is installed without ventilation, moisture "banked" in the siding can be driven through the vapor permeable house wrap by solar energy. "Solar vapor drive" works as a pump, that moves moisture into the wall assembly where it accumulates and cannot easily dry out. This creates a damp environment inside the wall that is ideal for mold and decay fungi.

This hidden decay often determines the lifespan of the structure. Unventilated installations can result in significant levels of decay in the sheathing and wall cavities in as little as 10 years. For this reason, some building departments now require "rain-screen" installations.

The Ecoshel Cedar Shingle System includes ventilation ridges on the back of the shingles. These hot melt beads  provide a slight gap between shingle layers, and between the shingles and the house wrap or felt. This built-in ventilation depressurizes solar vapor drive by allowing water vapor to vent to the exterior. The ventilation beads also function as baffles that prevent wind driven moisture from penetrating the shingle assembly.

As a true shingle installation, Ecoshel provides excellent protection in extreme weather. Shingle installations function as multiple layers of drainage planes, with each layer directing moisture back to the surface.  An Ecoshel installation provides this same level of protection for both roofing and siding. While more leak prone siding products benefit from the drainage plane that a rain-screen installation provides, the primary role of an Ecoshel rain-screen installation is to prevent trapped moisture and solar vapor drive. The built-in 0.10" rain-screen space works well to accomplish this.

Ecoshel's narrow rain-screen space simplifies construction, eliminating the need for door and window jamb extensions, as well as the need for screened vents at the base and top of the walls. The narrow space also minimizes the condensation potential, and reduces the ventilation requirement. An Ecoshel installation is continuously ventilated throughout the entire surface, providing an installation that is both highly weatherproof, and well ventilated.

Ecoshel's built-in ventilation system also provides a capillary break between shingle layers, which helps isolate moisture to the top layer, so the assembly dries out much faster than three saturated layers of shingles. Faster drying helps prevent decay. The capillary break also works to prevent trapped moisture between shingle layers. This helps prevent cupping that occurs when the sun dries the surface of the shingle while the back is still wet.