SPF Characteristics 102: Fiber Failures

A Check is a separation of the wood normally occurring across or through the rings of annual growth and usually a result of seasoning.  [Standard Grading Rules for Northeastern Lumber para. 704.0]

Surface Check – a check that occurs on the face of a piece of lumber.  [Standard Grading Rules for Northeastern Lumber para. 704.0 (a)]

Through Check – a check that extends from one surface of a piece of lumber to the opposite or adjoining surface.  [Standard Grading Rules for Northeastern Lumber para. 704.0 (b)]

Splits are defined as a separation of the wood through the end of the piece extending to the opposite surface or to an adjoining surface due to the tearing apart of the wood cells.  [Standard Grading Rules for Northeastern Lumber para. 740.0]

Shake is a lengthwise separation of the wood which occurs between or through the rings of an annual growth.  [Standard Grading Rules for Northeastern Lumber para. 740.0]

A Compression Failure is a check that occurs within compression wood, typically caused during the drying process or ordinary seasoning.

Timber Breaks are stress related fractures to the wood fiber which are believed to be a result of irrepressible forces applied to the living tree, such as sustained high winds, or the prevailing impacts, vibrations, and bending that can occur during felling.  The affected fibers of a Timber Break are not always perceptibly open or separated and it can be challenging to identify them in rough lumber; consequently, breaks are generally more visible in surfaced lumber.