Knots do not necessarily influence the stiffness of structural timber, this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain. COUNT 4
QSN1 What is wood's breaking strength susceptible to?  ANS1 defects QSN2 Depending on the placement and size of a knot, what property of structural timber can be affected? ANS2 stiffness QSN3 What do stiffness and elastic strength depend on more than defects? ANS3 sound wood QSN4 What direction of compression in relation to its grain won't weaken wood with sound knots in it? ANS4 parallel