- The moisture content of a piece of wood can affect its performance and properties including workability and strength, which will generally start to increase once the m/c falls below 25-30%.
- Moisture content is associated with shrinkage of timber seasoned beams as they will start to shrink as it falls below the 30% fibre saturation point. Pre-drying can avoid problems with this or the m/c can be measured to estimate the shrinkage that will occur.
- The susceptibility of timber to degrade by fungi or insect attack also depends on the moisture in the timber, as these both require the moisture content to be above 20%.
- As timber dries it becomes lighter and therefore easier to transport.
Recommendations as in BS 5268 Part 2
|End Use of Timber|
Av. m/c in Service (%)
Max. m/c at Time of Erection (%)
|External uses, fully exposed|
20 or more
Covered and generally unheated
Covered and generally heated
|Internal uses, continuously heated building|
Recording moisture content and shrinkage against time for ash. The shrinkage of exposed timber was compared to timber left under cover.