Structural Analysis of Historical Constructions – Anamnesis, diagnosis, therapy, controls – Van Balen & Verstrynge (Eds) © 2016Taylor & Francis Group, London, ISBN 978-1-138-02951-4 Conservation of timber structures in Istanbul: Problems and proposals I. Polat-Pekmezci, K.K. Eyüpgiller & C. Üstünda˘ g Faculty of Architecture, Istanbul Technical University, Istanbul, Turkey B.Y. Pekmezci Faculty of Civil Engineering, IstanbulTechnical University, Istanbul,Turkey ABSTRACT: Periodical monitoring and maintenance is a necessity for timber buildings to prevent severe damage and problems. Unfortunately, there is a lack of maintenance of timber buildings and this would become to a critical point if the building stays vacant or neglected for a period of time. Even the situation of the structure is not severe, during the preparation of conservation projects assessment of the timber structure becomes a necessity for accurate interventions. This paper would try to present the main problems of the timber buildings that have been investigated in the Bosporus area in the previous years in these terms. In the context, architectural loss, material loss and structural deformations of the investigated buildings would be described in detail. The paper also aims to display the difficulties that has to be braced during the assessment and the results of the mechanical tests including flexural and compressive strength carried out on the timber samples taken from different buildings with various health conditions in order to make a conclusion for an assessment method. 1 INTRODUCTION Istanbul has been inhabited since 8500 BC. Through the long history of the city, Bosporus has not only been a waterway within the city but one of the main elements that make out the image of the city. (Figure 1) The topography on both sides of Bosporus, with its hilly formation serves as a spectacular base for accelerating the impact of the architectural artifacts on each side. Historic neighborhoods, which have shown more development after 16th century, lengthen along the Bosporus. The shores are mostly occupied with monumental buildings such as mosques, palaces and waterfront residences (yalı ) while the neighborhoods extend to the sloping parts of the land. The urbaniza- tion process starting by 1950s has negatively affected the historical context along the Bosporus. By the 1970s the registration works of the timber structures along the Bosporus has begun. Despite the registration of the whole area of Bosporus as cultural and natural sites and the laws regarding the protection of the historic buildings defeated in 1983, after this date the area has suffered by serious planning intensions (Diker, Dinçer and Enlil, 2008). The high economic values and prestigious situations of the water by residences and monumental buildings in the region help their maintenance and good state of preservation. On the other hand, the timber build- ings those are smaller in size and located on the hills or inner parts are not that advantageous in terms of maintenance and care. On a broader perspective there are various fac- tors effecting the preservation of timber buildings in Istanbul such as :changes in the social and cultural Figure 1. Aerial view of Bosporus area (via Google earth). structure, economy, environmental factors, wrong interventions and lack of maintenance (Ya˘ gcı and Mazlum, 2016). However, this paper aims to dis- cuss the problems faced during the preparation of conservation projects of timber structures. Observa- tions on eleven timber structures will be evaluated and discussed in this manner. 2 THE NEED FOR THE ASSESMENT OF TIMBER BUILDINGS AND IDENTIFICATION OF THE PROBLEMS Within the legal framework inTurkey, the implementa- tion of a restoration project may start after the approval 1045