Thermal expansion of wood is insignificant in most cases. Consequently, it is seldom a consideration in the design of timber structures.
For oven dry wood, linear expansion parallel to the grain is usually within the range 0.0003% to 0.00045% per degC. Expansion across the grain is usually five to ten times that along the grain. Tangential expansion is greater than radial.
If the wood contains moisture, an increase in temperature usually causes a loss of moisture. This usually results in a net shrinkage, not expansion. Expansion joints should be provided if warranted.
References:
- Timber Datafile P1 – Timber Species and Properties of the NAFI Timber Manual.
- Bootle KR. Wood In Australia. McGraw Hill 1985.
