Abstract: A method and a pre-form for strengthening a substrate structural member. Layers are applied to a surface of a substrate where the layers include dry fibre reinforcement materials. A reduced pressure is then applied to the layers and a curable resin is introduced to the layers such that the resin is drawn therethrough until the interstices therein are substantially filled with the resin. The resin is then cured. The layers are preferably woven fabric and may include resin distribution layers of relatively low weave density and high permeability and reinforcement layers of higher weave density and lower permeability. The layers may be provided as a pre-form.