Knots and knotholes shall be absent from load-bearing structural timbers. Sound knots are permitted elsewhere. These shall be free from signs of decay, sound across the face, at least as hard as the surrounding wood and do not exceed 20 mm or ¼ the width of the face on which they occur, whichever is the smaller. Cluster or pin knots for decorative purposes may occur in non load-bearing components. Dead knots are not acceptable.
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