Potential defects

Almost every performance issue of timber used in construction occurs because:

1It was installed at the wrong moisture content for its application and movement occurs as it adjusts to its local environment or because;

2the component(s) 

Movement causes defects and moisture penetration and retention are the conditions that encourage fungal attack, decay and insects.

Timber cladding will perform perfectly satisfactorily over the life of a building so long as it has the appropriate durability rating. Durability can be either a natural characteristic of a particular species or it can be conferred on a species by preservative pre-treatment or a wood modification process.

It is important to remember that the sapwood of all wood species and the heartwood of many has insufficient natural durability for external applications but can be made highly durable by a wood protection process.