S&D Timber Merchants have always been at the forefront of enhancing and improving this basic structural timber product. Today all our carcassing is graded to comply with BS 5268, is stamped C16 or C24 (many productions are C24 only) Kiln Dried and Regularised with Eased Edges. All of which provides the end user with a product that is right for the job, complies with building regulations and is easy to handle.
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.
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.
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.
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.