Rocket Science: Understanding the Modern Cladding Support System
Presented by Brian Nelson, Knight Wall Systems
The presentation examines the purpose and intent of cladding support systems within rainscreen wall assemblies. It provides an overview of code compliance considerations for these assemblies, with a focus on cladding support systems, including the International Building Code (IBC), International Energy Conservation Code (IECC), and energy efficiency. This leads into a discussion on the thermal performance of various exterior wall assemblies, offering examples of strategies and tactics to enhance such performance. The second half of the presentation delves into factors influencing the design of support systems, including the cladding itself (layout, type, etc) and the loads that the support system must withstand.
How and Why Rainscreen Walls Work, or When They Don’t – A Deep Dive into the Building Science
Presented by Graham Finch, RDH
Rainscreen walls are systems made up of several materials that come together as a minimum building enclosure function to protect buildings from rain. Rainscreens must also manage environmental loads, including structural loads, fire and smoke, UV radiation, sound, heat flow, airflow, and vapor movement. Each of the system components, including the airspace between the outer and inner layers (aka the cavity or gap), are important to performance – and they need to work together to be effective.
The outer finish/cladding is the most visible rainscreen layer. This layer sheds water and provides the first line of protection of the underlying materials from the environment. If cladding gaps are added to an open rainscreen, extra water and UV gets past the outer layer and then managed with carefully selected materials and details. The structural attachment of the cladding through sub-framing and cladding attachments, and often exterior insulation, requires a thoughtful design that is balanced for thermal performance and structural efficiencies. Hidden behind the cladding is the critical airspace – the one “free” rainscreen component. This gap provides a clear path for water drainage and airflow through openings to the exterior. Most of the time, this system keeps the wall dry. If the air gap is oversized or attention isn’t taken with the selection of cladding or other materials, then this hidden cavity can become a fire concern. If the gap is too small, water can get trapped or airflow restricted, hindering performance. An inner water-resistive layer completes the rainscreen and acts as the last line of defense from water, and may also control airflow and vapor. Insulation placed within the rainscreen cavity for thermal benefit may widen the gap and impact water control decisions and the insulation materials may also have fire code ramifications. Some designers talk about pressure equalization as a solution for additional water management but find it difficult to achieve in practice. Pest management must also be considered in the openings and details and these screen openings can even tie into wildfire resistant construction details for rainscreen walls too.
Needless to say, a lot is going on within a rainscreen wall. This presentation uncovers how rainscreen walls work at a fundamental level and gets into the key design and construction considerations that make them perform as intended.
Water-Resistive Barriers, Last Line of Defense
Presented by Laverne Dalgleish, Air Barrier Assocation of America
Moisture damage is a leading cause of premature deterioration of buildings and can cause structural damage. Liquid water is the main culprit, but high humidity can have a role. Finding water leaks is not straightforward and liquid water shows up even when it is not raining. Material options abound to make buildings water-tight so why are there so many problems? This presentation provides options available to reduce water-leaks by properly specifying proper construction methods.
Mastering Prefabricated Rainscreen Walls
Presented by Rebecca M. G. Herkes and Peter M. Babaian, SGH
Prefabricated building enclosure systems continue to increase in popularity because they can help project teams streamline construction schedules, reduce construction costs, and improve assembly quality. However, for rainscreen walls, each layer comes with its own opportunity and associated considerations for prefabrication. It’s not always clear if prefabrication is the right choice for a given project or what impact it may have on the exterior wall performance. One of the key challenges in optimizing the value of prefabricated wall panels is selecting a strategy early in the design phase to appropriately set the expectations for cladding selection, scope of work coordination, and testing. In this presentation, we will categorize the wide range of rainscreen wall prefabrication approaches into three strategies that vary from the most field-intensive to the least field-intensive. For each strategy, we will discuss considerations for rainscreen cladding and compare the advantages and drawbacks of each strategy. We will review common issues such as thermal bridging and joint detailing. Finally, we will examine case studies to show how quality assurance processes may differ for projects with prefabricated exterior wall systems.
Elephant of Opportunities – Rainscreen Retrofit
presented by Jeff Kerr, Engineered Assemblies
This presentation will explore the rapidly growing field of rainscreen retrofits, a critical solution for enhancing the performance, sustainability, and aesthetics of existing buildings. Beginning with an introduction to rainscreen retrofits, the discussion will underscore the increasing necessity of updating older structures with modern rainscreen systems, emphasizing their significant impact on building performance and environmental sustainability. The panel will then address the “Elephant of Opportunities,” focusing on the market potential and environmental benefits that come with rainscreen retrofits.
The importance of rainscreen systems in recladding projects will also be a key topic, highlighting how these systems provide enhanced moisture management, improved overall building performance, and notable structural and aesthetic benefits. Panelists will share valuable insights on the best practices, common pitfalls, and innovative solutions in recladding with rainscreens, providing practical advice to industry professionals. The discussion will conclude with a series of case studies that showcase real-world examples and the lessons learned from successful rainscreen retrofit projects.