Cladding materials and systems

Cladding materials and systems, and the way these are attached to buildings, are fundamental to the success in keeping water out ie, complying with Clause E2 External Moisture of the Building Code.

While the Building Act does not make compulsory or ban any particular material or building design, the rigours of the New Zealand climate do make some materials and designs more suitable than others. Owners should be aware, when commissioning or buying buildings, that some materials and building features are more prone to leaking than others. This is not to say that these features will leak, but they will require more careful attention to ensure that water resisting systems are carefully designed-in and installed. Unless this is done, the risk of leaking is high.

More information will be available in our forthcoming publication, Principles of weathertightness.

In Acceptable Solution E2/AS1, Table 1 (known as ’the risk matrix’) outlines a list of such features and the degree of risk they provide in regard to weathertightness. Table 3 lists various common claddings and their relative suitability determined by their rated ‘risk score’. For more information see our publication, External moisture – a guide to using the risk matrix.

Selecting appropriate building designs and claddings will help reduce the risk of leaking. These two aspects taken together – risk feature and cladding type – form the basis of good weathertightness design. More information on this is available in our publication Constructing cavities for wall claddings.