Performance testing of cladding
Custom designed systems may require performance testing to prove that the intended design has adequate weathertightness.
In buildings where the cladding system is complex performance testing for weathertightness may be required as part of the contract conditions to demonstrate compliance with specified performance criteria. Many proprietary curtain wall systems also undergo performance testing to demonstrate compliance with current standards.
The testing regime depends on the type of cladding system.
In sealed systems (such as many forms of curtain walling) a representative sample of the wall, a minimum of one bay of the building, including all the details of the intended design is constructed. The tests generally include:
- Static pressure and water flow. A vacuum is applied to the rear of the sample and water flow is directed using a series of spray bar nozzles. The inside of the wall is then inspected for water leakage.
- Dynamic testing. The static test creates a positive pressure across the cladding, the dynamic test endeavours to create more realistic conditions by developing a turbulent pattern of wind driven rain across the external face of the cladding. In some test arrangements an aircraft engine is used to provide a dynamic wind pattern.
The testing regime for cladding is becoming more complex and may also include thermal cycling, structural movement and strength tests. (CWCT Standard and Guide for good practice for curtain walling.)
Multi-layered rainscreens have to be tested in a different manner.
Static water penetration testing is not appropriate to multi-layered rainscreens. Testing involves ensuring that each layer of the rainscreen performs as intended, for example the rainscreen layer will be tested for dynamic water penetration whilst the air barrier is tested for air permeability.
