a method of joining two components utilizes a fibrous preform at the joint . the preform has two lateral portions and a longitudinally extending flow path . the preform is sandwiched between the two components and enclosed within a vacuum bag . resin is introduced at an inlet of the flowpath while a vacuum pump creates a suction at an outlet end and along the lateral side edges . the flow path has greater permeability than the remaining portions of the preform , causing the resin to flow to the outlet end . when the resin reaches the outlet end , the suction at the outlet end is reduced , but the suction at the lateral edges remains without reduction to cause the resin to flow laterally into the preform .