We understand your confusion. So let’s break it down for you.
First of all, as we out here in Vancouver know, you need to protect your wall from the elements. Rain-screen siding is the first layer of defense against the elements, including rain, snow, sleet, wind and even the sun.
The idea behind rain-screen siding is simple — first, build an outside wall and weatherproof it (called a building envelope for those in the know) and then construct an outer layer of siding (the rain screen) to keep the weather away from the inner wall.
But here’s where lap siding and open-joint siding differ.
With our James Hardie lap siding (and optional cedar siding) that inner wall is wrapped with Tyvek HomeWrap, which protects the wall from outside water and seals the home from outside air. From there, the lap or cedar siding is built over it.
Open-joint siding provides extra layers of defense. 1/2″ ACX Exterior Grade Plywood added over the building envelope as an air and we then use state-of-the-art, industry-leading Reveal Shield wrapping to protect the building further.
The lightweight membranes allow vapor to permeate through, while still protecting the building from harmful moisture by allowing the vapor to then escape, reducing condensation.
Reveal Shield technology is easy to install in all climates, can be installed in tough conditions, are efficient to build, and will save energy in your building — according to a National Institute of Standards and Technology (NIST) study, air barriers save money and reduce energy consumption by as much as 40 percent per year over the life of the building.
The shield also reduces allergens by creating a healthy airflow.
James Hardie open-joint siding is then added over the wraps and fastened with stainless fasteners, completing the open-joint process.
The concept of rain-screen siding has been around since as early as the 12th century A.D. — but technology has advanced a lot further since then.