Cross-laminated timber (or CLT) must be recognized as a “precracked” wood composite material where the non-bonded edges within each layer act as cracks in the structure. Furthermore, differential shrinkage between the layers of installed CLT panels subjected to variations in moisture and temperature will result in additional cracks forming parallel to the initial precracks. Fortunately, there is a large literature on the effect of such cracks in cross-laminated composites used in aerospace composites. This paper applies prior literature (when available), and extends it (when needed) to derive all mechanical, thermal expansion, and moisture expansion properties of CLT as s function of the number of cracks in each layer. These results can be used to better design CLT structures. Furthermore, because CLT will form additional cracks when in service, these equations should be a key component of any durability analysis.
