It is a functional requirement of the building code – Clause E3 (internal Moisture) that buildings must be constructed to avoid the likelihood of:
1. Fungal growth or the accumulation of contaminants on linings and other building elements; and
2. Free water overflow penetrating to an adjoining household unit; and
3. Damage to building elements being caused by the presence of moisture.
E3.1 The objective of this provision is to— (a) Safeguard people against illness, injury, or loss of amenity that could result from accumulation of internal moisture.
That’s the code – however independent research in NZ, supported by extensive evidence in Canada and Europe clearly demonstrates that traditional New Zealand building techniques in colder climates does not comply with E3! Check out the independent WUFI Modelling Report demonstrating nationwide performance of traditional building materials: http://www.aridon.co.nz/specifiers.
We have a problem, it’s real, it’s been labelled the 2nd wave of leaky homes – and it can no longer be ignored!
HOW DOES MOISTURE PENETRATE THE BUILDING ENVELOPE?
Typically one of three ways:
1. Moisture present in building materials during construction and /or leaks.
2. From air leaks in the building envelope – a substantial volume of water vapour is carried by moist air entering the wall cavity either from inside or outside the building.
3. From vapour diffusion through building materials: Warm air vapour diffuses through vapour permeable building materials such as plasterboard interior wall linings.
Water vapour in the wall frame is not a problem in itself. Most walls are constructed from organic materials which are best kept in conditions which are healthy for humans. The problem occurs when water vapour meets cold surfaces (thermal bridges) or cold air and condensation (dew) forms. The term used to define when this occurs is the dew point.
HOW CAN WE STOP CONDENSATION FORMING IN OUR WALLS?
The safest way to prevent condensation forming in wall cavities is to keep the wall cavity warm and dry, to ensure the dew point does not sit inside wall cavity (which should be the dry zone of the building envelope).
The ARIDON® SMART WALL system wraps the outside of the building frame in a thermal weatherproof shell, which maintains the wall cavity at a temperature very similar to that of the room itself. The theoretical dew point of the ARIDON® SMART WALL system is near the exterior face (wet zone side) of the panel – exactly where it should be!
By removing the risk of condensation forming, water vapour can easily pass in and out of the wall cavity via plasterboard linings and maintain equilibrium with the internal environment – combatting interstitial condensation.
Canada has taken proactive steps to understanding the movement of moisture through the building envelope and changed their building code requirements/guidelines to ensure enhanced envelope performance can be achieved through insulating on the outside of the building frame, greater envelope airtightness and improved water management capabilities, amongst other factors.
So the key question is: If you know that your design is at high risk of mould growth and long term moisture loads within 18 months of completion, would you not look for a better solution?
ARIDON® SMART WALL – THE SMART CHOICE FOR EVERY BUILD