Delignification is the deterioration of timber brought about by the chemical breakdown and the separation of the cell walls of timber. It is brought about by airborne chemicals and it occurs in both softwood (pored) and hardwood (non pored) timber.

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

In coastal areas, Douglas Fir and Radiata Pine used in exterior situations are more likely to be affected.

A similar affect is sometimes noticed where industrial gasses and fumes are released into the environment, the result of some industrial manufacturing processes.

Combustion stove vapours and smoke will also cause lignin breakdown.

Long-term deterioration can result in timber collapse.

Improved ventilation and elimination of moisture discharged into the roof void will reduce delignification. Paint and other protective coatings will minimize exterior timbers being affected.

This material is subject to copyright. No reproduction, copying, altering or transmission of the above information is permitted without the prior written consent of the copyright owner.