The invention refers to a method of joining a nogging to a stud to form a sub-module of a prefabricated building module. The method comprises the acts of: providing (1000) a stud (2) and orienting the stud with a longitudinal extension of the stud along a first direction (A); providing (2000) a nogging material having a longitudinal extension being greater than an intended length of the nogging, and orienting the nogging material with a longitudinal extension along a second direction (B) being transverse to the first direction (A); moving (3000) a first free end of the nogging material into abutment with a first side surface of the stud (2) and cutting the nogging material to form a first nogging (3a); fixating (5000) and joining the free end of the nogging (3a) with the stud (2); moving (6000) the stud (2) and the first nogging (3a) along the first direction (A); and moving (7000) the free end of the nogging material into abutment with the stud (2); cutting (8000) the nogging material at a distance from the abutment, thereby forming a second nogging (3b); and fixating (9000) and joining the stud (2) and the second nogging (3b).