Dimensional lumber joist assembly comprising a dimensional lumber joist (12), weakened by the removal of a portion of its volume, and a reinforcement plate (10) attached thereto; the reinforcement plate (10) comprising a sheet-like material having a central opening therein aligned with the weakened portion of the joist, a plurality of elongate punch nail holes (60) through the material connecting the plate (10) to the timber (12) and characterised in that: at least a first elongate punch nail hole (60a) is arranged at an angle with respect to at least a second elongate punch nail hole (60b).