CWCT Sequence B Testing of Rainscreen Cladding Systems
At Sotech, selected Optima rainscreen cladding systems have undergone rigorous CWCT Sequence B testing, independently verified by UL Solutions, a global leader in safety and performance testing. CWCT Sequence B testing ensures every façade we supply is not only architecturally striking but also proven to deliver reliable performance under the toughest real-world conditions – including wind-driven rain, cyclic air pressure, and structural movement.
By specifying a CWCT-tested rainscreen system, architects, contractors, and developers gain independent, third-party assurance of quality. The result is greater confidence in design, reduced project risk, and performance that supports full compliance with UK building regulations and CWCT specification guidance.
What is the Step by Step CWCT Sequence B Testing Process?
1. Testing Rig Supplied by a certified test house, and SFS Framework installed
2. CP Board installed and fixed to SFS including built in window
3. Breather Membrane, support channel installed
4. Brackets and rails installed
5. Water Penetration – Static Pressure. Water is sprayed on the facade while increasing air pressure is applied behind the system, identifying leaks not visible under normal rain exposure
6. Water Penetration – Dynamic Aero Engine. Simulates high winds driving rain at angles ad speeds that mimic extreme weather events
7. Water Penetration – Hose. High-pressure water is sprayed onto the façade to reveal potential leaks under realistic driving rain conditions
8. Wind Serviceability & Safety – Measures the systems ability to withstand differential air pressures across the facades under varying environmental conditions
9. Air Leakage- Tests the facade for unwanted airflow under pressure.
10. Impact – Retention to Performance and Safety to Person
Why is Sequence B Testing Significant?
CWCT (Centre for Window and Cladding Technology) Sequence B is a comprehensive series of tests designed to assess the performance of curtain walling and rainscreen cladding systems under simulated environmental conditions.
When conducted by an independent body like UL Solutions, the testing provides third-party assurance that the systems will remain airtight, watertight, and structurally sound under:
- Prolonged water exposure
- Cyclic wind pressure (positive and negative)
- Air pressure differentials
- Dynamic wind loads
Unlike basic rainscreen system checks, CWCT Sequence B goes further – offering a realistic and repeatable simulation of real-world weather events, including wind-driven rain and structural movement.
Standard vs. CWCT Sequence B Testing
Comparison table
Feature |
Standard Rainscreen Testing |
CWCT Sequence B Testing |
|---|---|---|
| Water Management | Surface water control only | Wind-driven rain under pressure |
| Air Pressure Testing | Minimal pressure testing | Cyclical, increasing/decreasing pressure |
| Wind Load Simulation | Often limited or static | Cyclical, increasing/decreasing pressure |
| Structural Testing | Typically not included | Included: dynamic wind load testing |
| Certification | Often internal | Independently verified by UL Solutions |
| Best Use Case | Low-rise, low-exposure projects | High-rise, exposed, or mission-critical builds |
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