In comparison to boards made from 100% Wood, Hurd and Shive material the IB strength of the fiber-reinforced particleboards were significantly lower, approximately 30 and 41% for the Wood–Hemp and Wood–Flax (p < 0.0001), 29% for the Hurd–Hemp boards (p = 0.0087) and 46% for the Shive–Flax boards (p < 0.0001) respectively. The failure mode of the IB samples was predominantly delamination in the fiber layers. This is clearly seen. where the lower Flax layer has delaminated, likely a result of poor reisn distubution resulting in very weak resin free zones betweeen adjacent fibers