Understanding Condensation Risk
Long perceived to be immune from condensation problems, Australia has seen an increase in the occurrence and severity of condensation problems across dissimilar climate zones due to changes in building design and increases in energy efficiency targets.
Energy efficient construction increases condensation risk
The drive for energy efficient buildings has resulted in higher levels of insulation in the roof space and walls, as well as reduced air leakage due to modern energy conscious building practices. As a result, this has dramatically changed the temperature and moisture balance within buildings, which has increased the risk of condensation formation within the building structure.
The possible consequences of condensation and the subsequent high humidity environment include;
- Health Risks: Unseen mould growth behind wall linings and external cladding can be a health risk to the occupants, particularly the young or elderly.
- Visual Deterioration: Deflection or staining of plasterboard linings as a result of moisture trapped behind the linings can cause ugly stains and swelling.
- Structural Decay: Moisture trapped within the structure can result in long term corrosion of metal structures, timber rot, loosening of nails as timber swells, and cladding rot or swelling which can result in costly rectification work.
- Energy Efficiency: A reduction in the buildings energy efficiency can occur due to moisture saturation of the insulation, which can result in loss of thermal performance.
Where condensation forms in the building
In an energy efficient airtight building with a conditioned internal environment, moisture is added to the air by the occupants who are showering, cooking and breathing. Technically, we are expelling air; made up of nitrogen, oxygen and carbon dioxide (at an increased %) mixed with water vapour (gaseous water). This creates an internal environment with a higher vapour pressure than the outside environment which forces or ‘drives’ the water vapour in the
air outward in every direction looking for equilibrium.
As this vapour ‘drive’ occurs and forces moisture toward the cold outer surfaces of the building structure, impermeable materials such as glass, steel, plastic and traditional aluminium sarking materials cannot allow it to escape.
As a result, there is a risk that condensation can form on the inside of the building, just as mist or droplets of condensation form on the inside of a window on a cold night. To minimise this risk, the Enviroseal™ Wall Wrap membranes allow moisture to easily pass through the sarking with minimal resistance, allowing any condensation formation to occur on the outside of the building as shown in the following diagram.
What's the solution for controlling condensation?
Vapour permeable membranes are designed to allow moisture to pass through them whilst preventing the entry of wind driven rain and dust from the outside environment both during and after construction. When positioned against the outside of the building frames as a wall wrap or roof sarking, these membranes reduce the risk of condensation forming inside the building structure.
Enviroseal™ Wall Wrap key benefits:
- Condensation protection for a healthier structure
- Improves air tightness and energy efficiency
- Protects against the entry of wind, rain and dust
- Reduces the risk of unseen mould growth