Metalwërks Arcwall, an economical drained and back-ventilated rainscreen system for both walls and soffits manufactured from formed aluminum or stainless plate, were used in a UL certified test assembly using Rockwool mineral wool insulation, Tremco air barriers and Armatherm FRP Furring.
During the testing, one wall assembly was constructed and evaluated in accordance with the Standard, National Fire Protection Association (NFPA) 285 performance criteria are met.
NFPA 285 provides a method of determining the flammability characteristics of exterior wall assemblies, which contain combustible components.
The primary performance characteristics evaluated in this test were the capability of the test wall assembly to resist the following:
- Flame propagation over the exterior face of the wall system.
- Vertical flame propagation within the combustible components from one story to the next.
- Vertical flame propagation over the interior (room side) surface of the wall assembly from one story to the next.
- Lateral flame propagation from the compartment of fire origin to adjacent components or spaces.
Metalwërks Arcwall rainscreen panel system aluminum panels were installed on the exterior of the wall system. Panels measured nominally 0.125 in. (3.175 mm) thick. Each panel was fastened through the top extrusion to the horizontal non-metallic Z-girts by use of #12 by 1 in. (25.4 mm) long self-tapping screws. Each panel had 0.128 in. thick stiffeners attached to the back via fillet weld at the top flange and adhered using a black silicone sealant along the height of the panel.
Though Metalwërks’ panels are considered non-combustible, some elements of rainscreen wall assemblies can be considered combustible such as air barrier systems and non- metal furring such as Armatherm. These wall assemblies need to be tested to certify NFPA 285 performance criteria are met.
After all the devastating fires using ACM wall cladding and foam plastic insulation, meeting these requirements are now more diligently sought by design professionals, insurers and building code officials.