Rainscreen: Overview

The Rainscreen Principle is a method for controlling rain penetration through a wall cladding system. Also referred to as “open joint”, “dry joint” and “back ventilated”, a rainscreen building system is one where panels are attached to a fastening system (profiles) that creates air flow between the panels and a building’s structural wall. These open joints allow for expansion and contraction of the exterior panels and also enable air pressure in the cavity behind cladding to equal outside air pressure, resisting wind driven rain and other factors that can drive water into the building’s envelope such as gravity, kinetic surface tension and capillary action.

A rainscreen system uses a “double-wall construction”. The inner structural wall of the building is covered with a water-resistant barrier. The profiles are then attached to the structural wall and the exterior cladding is fixed to the profiles. The open joints between the exterior panels allow any rain that does penetrate to drain, evaporate or dry via “chimney effect”. A rainscreen system can improve the performance of the building’s interior climate by allowing moisture to escape and preventing mold formation. Rainscreen cladding also allows heat from the sun to be dispersed, which can prevent temperature fluctuations on the building’s interior and improve the overall energy efficiency of the building.

Rainscreen Panel Types

While rainscreen facades are a widely accepted building practice in Europe, this method only began gaining traction in the U.S. in 2007. Abet Laminati has been at the forefront with its durable Exterior Grade Phenolic (EGP) MEG wall panels which it first began manufacturing in 1995. MEG’s EGP panels are rigid, homogenous flat panels manufactured utilizing thermosetting resins reinforced with cellulose fibers. Produced under high temperature and pressure, MEG panels have integral properties and fire resistive qualities that make them ideal for use in exterior cladding systems.

Other types of materials such as fiber cement, terracotta, metal, and wood veneer can also be used to create a rainscreen façade. While panels may appear similar in form, they do not deliver equally in substance. For example, MEG panels and wood veneer panels look very similar, but are functionally very different. Veneer panels work well on building interiors while MEG panels are better suited for building exteriors because they are resistant to warpage, delamination, and chalking and are known to perform better over time.

How MEG Panels Are Made

MEG's exterior-grade phenolic panels consist of a core of Kraft paper and an exterior layer of decorative paper that are impregnated with thermosetting phenolic and melamine resins bonded together with heat and high pressure. Here is a brief overview of the process:

  • One-ton rolls of Kraft and decorative papers are placed on huge rollers called unwind stands.
  • The papers are unwound and treated. The Kraft paper that will make up the panel’s core is treated with a phenolic resin and the decorative paper that will make up the panel’s exterior is treated with melamine thermosetting resin.
  • Paper is treated as necessary to withstand ultraviolet rays.
  • The treated sheets are cut to length and several sheets of Kraft paper are hand-collated together with the decorative paper to make a panel. Approximately 50 sheets of Kraft paper and one decorative sheet are needed to make a standard 10mm MEG panel.
  • After collating, the panels go through a press cycle where they are baked at 325º under 1200 PSI. During this process, a cross-linking chemical reaction occurs and the phenolic and melamine resins bond to each other.
  • Then, the panels are factory trimmed and shipped to our warehouse in N.J.

* It is important to note that panels are shipped with a factory edge. All panels require complete fabrication as specified by the building design prior to installation.