Structures constructed from engineering materials such as reinforced and prestressed concrete, steel and cast iron, although durable, do have a finite life. Structures with significant problems are those exposed to marine environments, de-icing salts on highways, aggressive industrial environments and to a lesser extent those which are exposed to normal weather conditions. From an economic point of view it is generally more realistic to repair, if possible, rather than to demolish and rebuild the structures. The in situ rehabilitation or upgrading of reinforced concrete members using bonded steel plates has been proven in the field to be an effective, convenient and economic method of improving structural performance. However, disadvantages inherent in the use of steel have stimulated research into the possibility of using fibre reinforced polymer (FRP) materials in its place, providing a non-corrosive, more versatile strengthening system; it can also be used for prestressed concrete. This work presents a detailed study of the strengthening of reinforced concrete flat slabs using fibre reinforced polymer composite plates looking in the short term performance;in both serviceability.