Chemical Delignification. Also formerly known as “Defibration of Timber”.
Lignin is the natural glue that holds the fibres of timber together. Some airborne chemicals and salt air can have an effect upon lignin, causing the fibres to break down and separate from each other causing a rather ‘hairy’ appearance.

Timbers, which are used as tile battens, and rafters in roofing construction are most commonly affected. The timber surface exhibits orange coloured fibres. Delignification in roof cavities occurs more rapidly at higher temperatures.
This type of timber deterioration most often occurs in coastal regions and even areas several kilometers from the sea. Usually the affected timber is more than 20 years old.