What is a Rainscreen?

Eagle Aluminum Rain Screen Hat Channels

Rainscreens promote free airflow between a structure’s siding and an exterior water-resistant barrier. This allows moisture to escape, reducing the potential for moisture-related damage.

Rainscreen systems create an air gap between a structure’s siding and a water-resistant barrier like asphalt felt or house wrap. Although not every building requires this gap, a rainscreen is always an advantage because it provides additional ventilation for moisture that might otherwise become trapped. Trapped moisture can cause building materials to rot, warp, rust, and lead to mold and mildew buildup.

 Basic elements of rainscreen systems

  • Siding or other exterior cladding
  • Furring channels (often hat channels)
  • A water-resistant barrier

Industries that Use Rainscreen Systems

  • Commercial builders
  • General contractors
  • Architectural design
  • Restaurant & hospitality
  • Masonry

When are rainscreen systems used?

Almost all modern commercial buildings use rainscreen ventilation to prevent damage from moisture buildup. In wet climates and climates with drastic temperature changes, residential construction also commonly incorporates rainscreens. Dramatic weather changes can create excess condensation especially during the fall and spring seasons. Condensation buildup can also occur in winter and summer months when heating and air conditioning cause a large temperature difference between the interior and exterior of a building.

Rainscreen Systems Promote Ventilation

Builders and architectural designers frequently use hat channels to create a gap for rainscreen ventilation. Channels run both vertically and horizontally to allow air and moisture to escape through all four (or more) edges on the side of a building. The open channels on residential rainscreen systems promote free airflow through the gaps and help to dry both the sheathing/sheeting and the siding itself. Since aluminum is incredibly resistant to rust, warping, mold, and mildew, the aluminum hat channels themselves are not subject to moisture damage.

Harmful effects of moisture buildup

  • Mold and mildew
  • Rust
  • Rotting
  • Warping
  • Bug infestations
  • Reduced air quality (this can become a serious health hazard)

Why does rainscreen ventilation work?

The chimney effect is most responsible for the success of rainscreen systems. Also called the stack effect, the chimney effect explains the flow of air in a column as the air temperature changes. Because warm air is more buoyant than cool air, it rises upward and escapes through any gap available. Warm air also tends to contain more moisture (steam) thanks to the evaporation process, which depends on heat. The chimney effect is most effective in direct sunlight because sunlight causes a building’s exterior and the air behind it to heat more quickly.

Eagle Mouldings is a manufacturer, stocking warehouse, and supplier of custom and OEM aluminum extrusions. If we don’t have the extruded aluminum part that meets your specifications, our professionals will help you create and engineer one to meet your needs. Our custom and OEM extrusion services enable us to meet nearly any aluminum extrusion needs our customers may have.