Japanese temples are generally characterized by long overhanging roof eaves covered with heavy clay tiles. The weight of these roofs creates unusual stresses on the supporting structures. Consequently, the buildings require roof replacement every 50 to 70 years and major overhaul every 200 to 300 years. The building structures are usually made from large dimensional timber. Prior to restoration the stresses are carefuly analyzed. To preserve the historic configuration of the buildings the structures are reinforced with ingeniously concealed steel trusses. During the restoration work, enclosures are erected over entire buildings. These enclosures protect the invaluable artifacts from the elements and permit the continuation of construction under all weather conditions. The unique reinforcing techniques used at the Todai-ji Temple, The Five-storied Pagoda and Main pavillion of the Horyu-ji Temple and the Main-gate of the Tohfuku-ji Temple are described.