Why Kiln Dried?
By drying timber to below 20% moisture content any risk of shrinkage in situ is greatly reduced thus eliminating remedial work at a later date.
Why Graded?
Timber must be graded (and dried) if it's to be used in internal structural applications as stipulated by building regulations. Timber is graded to either C16 or C24. Here all the structural properties of the timber are quantified. Eg Species, Knot Size and Type, Slope of Grain, Tightness of grain, Compression Wood, Rot etc. C24 grade can only be achieved by imported timber. Homegrown timber from UK sawmills will make C16 only and so will have reduced span capability.
Why Regularised?
Although the sawing process is a lot more accurate than it was some years ago, by regularising the timber the end user can be sure that in whatever application each piece will have consistent and "regular' size. It is also more visually appealing.
Why Eased Edges?
Putting eased or rounded edges on a piece of timber has no structural advantage. Its done simply to make the manual handling of the timber a little easier.
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