AITC Technical Note 18, titled “Evaluation of Checks in Structural Glued Laminated Timbers,” provides guidelines on the significance of checks in glued laminated timber members.
In general, checks have a limited effect on the strength of glued laminated timbers. In bending members, checks affect only the horizontal shear strength and are only of structural importance if the checks are deep or occur near the mid-depth of the member near its support1. In compression members, checks are of structural significance only if they develop into a split that increases the slenderness ratio of the member. If a preliminary inspection indicates that checks appear to fit either of these situations, a detailed evaluation should be performed by a qualified design professional.
The moisture content of the member at the time of inspection should be measured and recorded to determine the magnitude of drying that has occurred relative to the original moisture content at the time of manufacturing and to the expected equilibrium moisture content of the structure.