Rising Trends in Ventilated Rainscreen Systems
For a building of any kind, the first line of defense protecting its occupants from the elements is the external cladding. It is a critical component of the overall structure that must be designed to ward off wind, rain, snow, cold, heat, moisture, and more.
As an external wall assembly, rainscreens have been around for decades, but advancements in technology have made them increasingly popular. This is due to two key factors—their ability to deliver optimal performance metrics and the flexibility they provide when it comes to design options.
At its most basic level, a rainscreen is an exterior wall configuration on any structure where the cladding is installed such that it stands off from the moisture-resistant barrier on the external wall sufficient for the passive removal of water and vapor. This creates a break between the cladding and the outer wall, an air gap designed to allow for drainage and evaporation. In today’s marketplace, a rainscreen must deliver much more than just protection from the elements.
Architects, specifiers, and designers are constantly weighing competing forces on every one of their projects. They must be able to quantify the anticipated long-term performance of the building envelope such that it will keep the occupants safe and comfortable. When building to Passive House standards, product choices must also account for the demands for greater energy efficiency, enhanced durability, the constant cost pressures to deliver on time and on budget for every project, and the need to create a signature look that will make the building stand out.
Several trends demonstrate how rainscreens are emerging as a preferred solution within the Passive House community and beyond due to their ability to eliminate complexity, achieve cost savings, and deliver on curb appeal.
A System Approach
Cutting-edge ventilated rainscreen enclosure systems are engineered to provide superior weather protection and thermal performance. A successful rainscreen system is comprised of five layers:
· Air and moisture barrier to keep water outside the building. This layer is often fluid-applied, adhere membranes, or factor-bonded with the barrier.
· Subconstruction, or furring, with mounting brackets anchored into substrate to connect the cladding.
· Insulation of varying thickness between brackets, rails, and subconstruction where required by code or as a means to achieve Passive House certification.
· Air and ventilation cavity—the most important layer—that serves as a drain and vent space engineered into the envelope.
· Durable and water-shedding cladding to protect against environmental elements, UV exposure, pollutants, and more.
In the past, contractors and specifiers would bring in a different manufacturer and installer for each of the five layers, complicating the construction process and follow-up coordination. A two-look façade could include up to ten manufacturers—requiring additional documentation and coordination on all levels, multiple warranties to balance, and added scheduling to juggle.
However, that is changing as the success and ease of a system approach rises in popularity. Some manufacturers now offer smartly engineered building enclosure systems that contain all of these control layer components in an integrated and fully tested system. As a single solution, the individual layers work in concert with each other to deliver a holistic approach.
A single-solution rainscreen system also means that architects and builders are dealing with only one warranty and one manufacturer. Designers know the solution does not require them to do additional research and testing to ensure they meet applicable codes and performance standards for certification. Additionally, when the same installer puts on all five layers, there is less guesswork and more certainty in construction leading to less time on site and lower installation costs.