A rainscreen is a core strategy in modern wall design. It adds a drained and ventilated cavity that works alongside the air and water barrier. Without that cavity, water that seeps behind cladding remains trapped, creating long-term risks for building durability and performance.
What Is a Rainscreen and Why It Matters
A rainscreen creates a space between the exterior cladding and the air or water barrier that allows water to drain and air to circulate.
- When built correctly, this cavity acts as a capillary break, stopping water from migrating inward and giving the wall assembly drying potential.
- Building codes in many jurisdictions now require this approach behind absorptive materials such as stucco, adhered stone veneer, and manufactured stone, ensuring consistent performance under repeated wetting events.
This approach addresses both drainage and ventilation. By keeping moisture away from the weather resistant barrier (WRB) and providing airflow through the cavity, a rain screen wall system enhances drying potential and extends envelope service life.
Core Components in a Rain Screen Wall System
Every system has three fundamental elements that work together to manage bulk water and promote drying.
Cladding and Attachment
The cladding is the outward-facing material—fiber cement, terracotta, masonry veneer, or metal panel. It connects to the structure through furring strips, girts, or proprietary attachment systems that maintain cavity depth and enable airflow.
Continuous Drainage and Ventilation Cavity
This cavity only works when it provides a clear vertical path for water to drain from top to bottom. Vent openings at both ends promote drying, and insect screens, flashings, and proper vent detailing keep pests and rain out.
Air and Water Barrier Continuity
Behind the cavity lies the air and water barrier—sheet-applied, fluid-applied, or integrated WRB. Flashing and terminations need tight integration with this barrier so the rain screen system can manage bulk water effectively while protecting envelope integrity.
Drained & Vented vs. Pressure-Moderated Systems
Different approaches to rain screen construction exist, but most fall into two broad categories.
- Drained and ventilated cavities are most common, relying on gravity and airflow to remove water.
- Pressure-moderated systems add vent strategies to reduce pressure differences across the cladding.
Both rely on uninterrupted airflow and open vent paths. In the field, detailing and installation discipline determine performance, not just design intent.
Where Codes Drive Use of Rainscreens
Building codes often reference rain screen wall systems when they emphasize the need for drainage spaces. Jurisdictions in wetter climates frequently require these assemblies behind absorptive claddings.
- For example, some regions mandate a one-inch cavity behind stucco or stone veneer.
- Even where not mandated, designers recognize that a drained and ventilated cavity protects the air and water barrier, reduces moisture exposure, and improves drying.
Because local amendments vary, confirming cavity depth, ventilation, and flashing details is essential for compliance.
Rainscreen System Details That Prevent Callbacks
Performance depends on attention at transition points:
Windows and Doors
At heads, cavity continuity must be preserved using flashing and venting. At sills, water must be directed outward. At jambs, properly integrated membranes and back dams help prevent leaks.
Penetrations and Fasteners
Vents, service lines, and fasteners should be treated so the barrier and cavity remain functional. Sealants or flashing strategies must account for penetrations through the WRB.
Base of Wall and Parapets
Drainage outlets such as weeps or open head joints must align with the cavity. Insect screens prevent intrusion, and kick-out flashing ensures water is directed out of the wall system. At parapets, top vents provide airflow while shielding against rain entry.
Construction Sequencing and Field QA/QC
Installation order strongly affects performance. The barrier must be installed, inspected, and tested before cavity supports are attached. Installing furring or girts too early creates penetrations that may never be sealed.
During construction, confirm drainage paths remain open, vent locations align, and flashing overlaps correctly. At project closeout, visual inspections should verify cavity continuity, treated penetrations, and unobstructed drainage outlets.
Design Considerations for Rain Screen Systems
From material compatibility to aesthetics, a rain screen system shapes both performance and appearance.
- Continuous insulation may sit behind cladding, but attachments must not compress the cavity or restrict airflow.
- Fire resistance, structural requirements, and energy code compliance all guide detailing decisions.
A rainscreen does not eliminate the need for an air and water barrier.
- The cavity controls bulk water, but the WRB ensures air tightness and weather protection.
- Codes often require cavity systems behind absorptive claddings, yet even when optional, they provide resilience by reducing moisture risk.
These systems deliver benefits in all climate zones, since even dry or cold regions encounter wetting events that benefit from cavity drainage and ventilation.
Two PROSOCO Rain Screen Products: Integrated & Fluid-Applied Solutions
Prosoco supports rain screen wall assemblies with air and water barrier products engineered for durability and ease of application.
- Cat 5 Rain Screen — A fluid-applied, single-component STP (Silyl-Terminated Polymer) membrane that bonds to damp substrates, delivers seamless adhesion, self-seals around fasteners, and withstands conditions up to 155 mph hurricane-level weather.
- Spray Wrap Rain Screen — A spray-applied, elastomeric membrane that dries into a vapor-permeable, rubberized coating. It minimizes condensation, supports drying of trapped moisture, and reduces energy loss.
Each works as the primary air and water barrier under open-jointed cladding assemblies, simplifying installation and enhancing envelope resilience.
Work With PROSOCO Rainscreen Solutions to Build Durable Walls
Our team helps design and deliver building envelopes that resist water intrusion and perform over decades of service. We focus on practical products that ensure drainage, drying, and barrier continuity on real job sites. Contact us today for more information.