The Effect of Moisture Content on the Tensile Strength of Sitka Spruce: A Report on Research Carried Out on Aircraft Quality Sitka Spruce Available to Purchase

IT is well known that the strength properties of timber arc affected by the amount of moisture it contains. This effect has been investigated comprehensively for the strength properties of compression, bending and impact, and the results from a number of species have shown that the relation between these strength properties and moisture content can be expressed as an exponen‐tial equation. These properties have been shown to decrease as the moisture content increases to the ‘intersection point’, which corresponds roughly to the fibre saturation point, and to re‐main unaffected by further increase. The equation which defines the relationship up to the inter‐section point is of the form: