When the air inside a building is warmer than the metal cladding, water vapor in the air can condense on the interior surface of the cladding.
Water vapor typically moves freely through most building materials into ceiling and wall cavities, where it can directly contact the cladding.
Condensation can cause damage to building components and lead to staining on ceilings and walls. If insulation blankets or batts become wet or even slightly damp due to condensation, their efficiency is significantly reduced.
The amount of condensation that occurs depends on the level of water vapor in the air, which fluctuates with climatic conditions. Activities within the building, such as bathing, showering, cooking, washing and drying clothes and dishes, and even breathing, can significantly increase the amount of water vapor. Therefore, it’s important to vent substantial amounts of water vapor outside the building.
To reduce the risk of condensation on the underside of roofing, a vapor barrier is often used to prevent warm, moist air from coming into contact with the roofing material. Reflective foil laminate is commonly used for this purpose.
To further reduce condensation on the underside of the laminate, it should be draped between roof supports so that the cold cladding does not come into direct contact with the laminate, except at the support points.
To learn more about Condensation Management please review the following documents;
For further details you can reference the following ASI Fact Sheets;
- Metal-roofing-and-condensation.pdf (steel.org.au)
- Vapour-barriers-and-metal-roofs.pdf (steel.org.au)
- Blanket-and-foil-insulation-of-metal-roofing.pdf (steel.org.au)
- Fact-Sheet-Eave-Ventilation.pdf (steel.org.au)
Ventilation Devices available from Fielders;
- Corex Cor-Vent® - Cor-Vent® Standard Pitch Roof & Cor-Vent® Low Pitch Roof
- Vent-a-Roof
- Karben Ember Mesh
- Bradford Wind Master Roof Ventilator
- Ampelite Spinaway and Superflow Roof Ventilators
Availability varies nationally, please check with your local branch for your ventilation device options.