While the construction of timber houses had been promoted throughout the long history of Istanbul as a response to the fact that the city is situated on a seismic fault, wood as a construction material has been gradually abandoned due to the many disastrous fires the city has experienced. Even so, the timber residences and the urban fabric they once formed traditionally constituted one of the main distinguishing features of Istanbul. These houses are now greatly valued as an element of Turkey's cultural heritage. The districts of Zeyrek and Suleymaye, two of the four areas of Istanbul that were included on UNESCO's World Heritage List in 1985, have urban fabrics predominantly consisting of timber houses. Despite this status, however, the timber houses in these areas could not be preserved with their original construction techniques and details. In this article Istanbul's traditional residential architecture is examined in terms of its value as a cultural heritage and a determination is made of the factors threatening these values. Two original examples that have been examined in detail, on the basis of their historical development and current features, are presented and the preservation problems encountered by timber houses in Istanbul are examined through these examples.