Wet Seals for metal composite material systems

Wet Seal System are one of the original MCM installation systems, along with dry seals, used for around 40 years in the US and still widely used today. Also known as a “single line barrier wall” or “fully-sealed wall”, wet seal systems are installed with a joint located between adjacent panels that is fully sealed with exposed sealant. Tested in the US to AAMA 501 & 501.1 standards, in the UK fire class tests will likely be according to Euroclass A1 or A2, A or B as the lower rating.

The Centre for Window and Cladding Technology (CWCT) defines a rainscreen cladding system as '...a wall comprising an outer skin of panels and an airtight insulated backing wall separated by a ventilated cavity. Some water may penetrate into the cavity but the rainscreen is intended to provide protection from direct rain'.

The Metal Constuction Association, Technical Bulletin MCM Panel System Definitions, dated March 2018 describes the design and functions of MCM Wet Seal Systems as thus:

"This installation type creates a single barrier between the exterior environment and the interior cavity behind the panel. Air and water infiltration is minimized by the flexible exposed sealant located at each panel joint. In this type of system, the sealant installation and adhesion to the panel on each side of the joint is critical for successful performance. This type of installation should be inspected regularly to make sure that the sealant has not lost flexibility or adhesion to the panel as the exterior envelope ages."

"The Wet Seal system is intended to stop water infiltration at the exterior panel surface; however any water or condensation that may find its way into the panel cavity gathers at the sill flashing. A well designed Wet Seal system will generally include the use of properly designed sill flashings with weep tubes to allow unwanted water to exit. The use of an air/water barrier is generally recommended to protect the panel cavity from moisture damage; however the wall assembly should be tested without this additional barrier in place so that performance of the exterior cladding assembly may be determined isolated from the air/water barrier performance."

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