Building Construction Handbook, Eighth Edition

Wane or waney edge ~ occurs on timber cut close to the outer

surface of the log producing incomplete corners. Measurement is

parallel to the edge or face of section and it is expressed as a

fraction of the surface dimension.

Growth rate ~ measurement is applied to the annual growth ring

separation averaged over a line 75 mm long. If pith is present the

line should commence 25 mm beyond and if 75 mm is impractical to

achieve, the longest possible line is taken.

Pith A

D

B

25mm C

75mm

AD B

C if pith is absent measure 75mmthrough centre of the end of timber

Wane is

expressed

as: A+B

C

D = 2C

3 minimum

Distortion ~ measurement over the length and width of section to

determine the amount of bow, spring and twist.

2m

2m

Bow

Spring

Twist

2m

Materials Testing---Softwood Timber Grading---3