Traditional methods of restoring historical buildings typically consisted in replacing the damaged elements or additional steel and reinforced concrete elements were inserted into the old structure. They significantly interfered with the statics and aesthetics of buildings. Current composite materials used in restoration damage the old structure only slightly and can usually be removed in the future. Due to these advantages they comply with the conservation lawin force. This paper presents a few examples of practical applications of composites the authors have designed for structural reinforcement and protection of historical buildings. Repairs of columns, vaults, masonry walls, stone facades and wooden beams with the use of steel screw-shaped bars and high strength fibres in epoxy resin or cement matrix were presented. Problems of ensuring the proper bond of the composite to the old substrate and insufficient coverage of the fibers with the cement matrix were considered. Although the threats and structural damages which occur in most historical buildings tend to be similar, individual design solutions are required in each case. Historical investigation and detailed measurement of geometry and deflections have to be made before choosing the appropriate method of reinforcing the old structure. It can be predicted that prestressing composite materials used for historical structures will also be applied.

Tension-strut systems consist of thin cables and membranes capable of carrying only tensile forces and compressed struts cooperating with them. They make very effective use of strength properties of materials. They are lightweight and common in large span structures such as bridges and stadium roofs. However, they may also be advantageous in reinforcing and repairing historical buildings as they conform to conservation law in force. This paper presents a few examples of such applications of tension-strut system. Stabilization of historic brick and stone vaults with buttresses and iron bowstrings often turns out inadequate to resist thrust forces transmitted from the vault to the walls which cause cracks and deformations of the vault. Properly designed tension-strut structure can resist the thrust forces calculated in a theoretical way. Moreover, it can be hidden in the attic of building. Old timber roof structures are usually deformed and excessively deflected. Skilfully assembled tensionstrut systems enable straightening and geometrical adjustment of a roof structure. Although similar threats and structural damages occur in most buildings which are a few hundred years old, individual design solutions are required in each case. Historical investigation and detailed measurement of geometry and deflections have to be made before choosing the apprioprate method of reinforcing the old structure.