Commercial rainscreens are exterior cladding systems designed to protect buildings from moisture and enhance their appearance. Their main purpose is to provide an extra layer of protection, manage air and water, and improve the aesthetic of the building or structure.
They consist of a variety of materials and components to create a protective barrier against rain, wind, and other elements. Rainscreen systems are commonly used in commercial construction for buildings like offices, schools, hospitals, and retail centers to provide much-needed ventilation and drainage. The designs are unique to each project and its specific goals and the systems can vary greatly depending on the environment and type of structure.
Rainscreen systems offer architects and designers a wide range of options for exterior finishes and materials, allowing for creativity and customization in building design.
Types and benefits
The outermost layer of the cladding system can be a variety of materials and may include metal panels, metal composite materials (MCM), fiber cement boards, stone or other organic materials, polycarbonate panels, and even glass blocks.
The support structure provides the framework for attaching the cladding panels and other components of the rainscreen system to the building and typically consists of metal studs, framing members, or other structural materials. The support structure may or may not be provided by the rainscreen manufacturer.
Installing rainscreens provides important benefits such as the following:
Moisture protection
The rainscreen panel is the primary barrier against moisture penetration. It is installed over the building’s weather-resistant barrier (WRB), providing space between itself and the building envelope. This gap allows for airflow and drainage, helping to prevent moisture buildup. Ventilation openings are strategically placed within the system to facilitate airflow behind the panels. Ventilation helps to remove moisture and aids in drying moisture that penetrates the exterior surface.
Thermal performance improvement
The interior space between a rainscreen system and the building envelope can improve the thermal performance of a building by providing additional insulation. Flashing materials are used to seal joints and transitions between different components of the rainscreen system, such as where the panels meet windows, doors, or other building elements. Sealants are applied to further waterproof these connections and prevent water infiltration.
Additional long-term exterior protection
Many rainscreen materials are highly durable and resistant to weathering, providing long-term protection for the building envelope.
Design and engineering considerations
Designing and engineering rainscreen systems requires careful consideration of several key factors to ensure proper performance and durability, including the following:
Codes and regulations
Local building codes, regulations, and industry standards that govern the design and construction of rainscreen systems should be considered before designing a system. Ensure compliance with requirements related to structural integrity, fire safety, wind resistance, and
energy efficiency.
Climate
Another important factor to consider is the local climate conditions, including temperature fluctuations, humidity levels, rainfall patterns, wind loads, and exposure to sunlight. The rainscreen system should be engineered to withstand these environmental factors and provide adequate protection against moisture, thermal bridging, and UV degradation.
Understanding code requirements and the climate will allow designers and manufacturers to work together to choose appropriate materials for the rainscreen cladding panels, supporting framework, and additional components. Materials should be chosen based on their performance characteristics, durability, maintenance requirements, and aesthetic considerations. For example, a designer who wants a backlit polycarbonate wall system should consult with a manufacturer to determine the appropriate system that includes UV-resistant panels and a framing system to allow for thermal expansion and water management.
Other factors to consider include material compatibility, corrosion resistance, and fire resistance.
Fire resistance
The fire resistance properties of the rainscreen materials and components should be evaluated in accordance with applicable fire codes and standards. Fire-rated materials can be specified as necessary to prevent the spread of fire and smoke within the building envelope.
Structural strength
The structural components of the rainscreen system—including the supporting framework and attachment methods—should be able to withstand anticipated loads and forces, such as wind loads, seismic activity (if applicable), and thermal expansion and contraction. Ensure proper anchorage to the building structure and consider factors such as deflection, creep, and fatigue.
Drainage, airflow, and thermal performance
The system should be designed to provide drainage, an air gap, and ventilation channels behind the cladding panels to facilitate airflow and drainage. Additionally, consider the thermal performance of the rainscreen system and its impact on the building’s energy efficiency, indoor comfort, and HVAC requirements. Design the system to minimize thermal bridging, optimize insulation levels, and incorporate thermal breaks and air seals to enhance thermal performance and prevent heat loss or gain.
Material compatibility
The design and engineering of the rainscreen system should be coordinated with other building systems and components—such as windows, doors, roofing, and exterior finishes—to ensure compatibility and seamless integration to achieve a cohesive building envelope.
Quality assurance
Depending on the specific application, rainscreen systems may undergo quality assurance procedures and testing prior to installation. Mock-ups can be designed and tested to identify any potential issues and verify the performance, durability, and compliance of the system.
Installation, maintenance, and performance
Rainscreens that are prefabricated carry an advantage over systems that are fabricated on-site. Prefabricated systems lessen installation time and ensure optimal performance.
Installation of a rainscreen is dependent upon the manufacturer’s specific installation guidelines and the materials are chosen, for proper performance. Installation typically involves attaching cladding panels to a framework and integrating flashings and trim while ensuring there is proper ventilation and drainage.
Long-term maintenance with rainscreens involves regular inspection to ensure durability and continued performance. It is important to follow the manufacturer’s cleaning instructions for removing debris from the cladding and clearing any blockages that may affect drainage.
Rainscreens should be covered by a manufacturer’s warranty, which will vary depending upon the type of system. Check with the manufacturer to see what is covered in the system warranty.
Checking with experienced building envelope consultants and manufacturers to assist with the design, engineering, and specification of the system can alleviate any concerns. Their expertise can help address technical challenges, optimize performance, and ensure successful installation.
Victoria Scanlon is the marketing manager for EXTECH/Exterior Technologies. Since its inception in 1975, EXTECH/Exterior Technologies, Inc. has been at the forefront of architectural innovation, specializing in custom facade systems, translucent walls, windows, skylights, and canopies that blend aesthetics with functionality. Operating from its Pittsburgh headquarters and a strategic Las Vegas office, EXTECH serves a nationwide clientele, continually pushing the envelope of architectural design. Scanlon can be reached at vscanlon@extechinc.com.
