In calculating the timber content of a cutting list for costing purposes the appropriate wastage factors must be added. Whereas softwood in scantling dimensions may need from only 5 to 10 per cent addition, square-edge hardwoods will require 15 to 20 per cent, and most waney or wane edge boards and planks 60 per cent, with the exception of certain wasteful timbers— walnut, rosewood in the log, etc.—where the true waste factor may be as high as 200 per cent. Plywoods, blockboards, etc. bought carefully to suit the dimensions needed may only require 10 per cent, but an average 20 per cent is safer, while most veneers will need at least 50 per cent. Where there is any doubt it is always better to debit the whole planks, sheets or leaves to the job and credit back the usable surplus, not including rippings and off cuts.
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