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Defects while the tree grows

Trees can inherently develop defects due to the processes and conditions it faces in its history. Dr Zahir discusses.
© Universiti Malaya

Timber grows naturally and takes a long time to mature into usable building material. Defects could happen inherently due to natural occurrence that affected the tree throughout its history.

A tree that grows with little disturbances will have less defects and will look ‘clean’.

Inherent defects

Inherent defects are defects that occurs naturally during the growth of the tree. While a tree grows, there might be a tree that fell and leans against its trunk for quite a while, causing uneven ring patterns. There might be forest fires that damages the tree but it survived, causing discolouration of the rings or even weak spot that causes shakes. There could also be a period of rapid growth due to favouring conditions or slow growth caused by draught and other natural disaster. Insects and other biological agent can also affect trees causing defects.

These defects cannot be controlled but there are ways to remedy them to make full use of the timber. These are explained in the infographic below.

Knots are dead and damaged branch bases that remains in tree during its growth. Dead knots especially are detrimental to timber strength.

Veins are a build-up of tree resin or sap that presents in a different colour to the timber surrounding it. It is also a weak point with less timber fibre in them.

Gum pockets or blotches are accumulation of sap that is contained within the timber structure and have less strength as it does not contain wood fibres.

© Universiti Malaya
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Building Pathology: The Science Behind Why Buildings Fail

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