The average builder usually installs siding right up against the housewrap because it’s fast, easy, and cheap. But it might be time to step up your game a bit and consider creating a rainscreen.
A rainscreen, also known as a ventilated façade in Europe, is a system of installing cladding that, in effect, creates a double wall with about a 1- to 3-inch space of air between the siding and the exterior wall.
“Rather than attacking the symptoms of moisture intrusion, rainscreens tackle the source—the forces that drive water into the building shell,” ToolBase Services, the technical information resource of the NAHB Research Center in Upper Marlboro, Md., says on its website. The way it works is that the pressure behind the cladding is equalized with the exterior so wind does not get a chance to force moisture into the home.
The system, ToolBase says, includes a porous exterior cladding, an air cavity, a drainage layer on the support wall, and a rigid, water-resistant, airtight, support wall.
Porous cladding? Why would you deliberately make your siding porous? The air that passes in and out of the siding offers a variety of benefits: It allows the side wall to dry out quickly, which prevents moisture intrusion and decay, and it also allows moisture inside the home to escape.
In addition to providing moisture protection, a rainscreen is “an exceptional reflector of solar radiation,” says Louisville, Ky.–based Cement Board Fabricators, which offers cladding for rainscreens. “The heat accumulates on the surface layer and is not passed onto the underlying layers.” Air flowing behind the cladding then allows the heat to escape, resulting in cooler homes.
A rainscreen is well suited to most climates, but it will increase the effort to make the building airtight and the material cost for furring out the wall. Still, ToolBase says it is worth it.
“The few cents per square foot spent on a rainscreen offers exceptional value to design professionals seeking liability protection, builders wanting to avoid callbacks, and homeowners looking for comfort.”
Revealing Design: Designed for multifamily and light-commercial projects, Hardie Reveal is a fiber-cement cladding system that consists of panels and Fry Reglet aluminum trims. Available in 4-foot-by-8-foot sizes, the panels are made from wood pulp, sand, cement, and water, but it’s 40 percent thicker than residential fiber cement. It can be field painted or come prefinished in 26 colors. James Hardie Commercial. 888-542-7343. www.jameshardiecommercial.com.