This research examines the longhouses of the Ibans who live in Sarawak, Malaysia. These longhouses are highly regarded by antropologist because of its atypical social structure. Bilik family is not related to matrilineal or patrilineal, where men and women has equal right to the bilik. This report clarifies the following points; firstly, the influence of the cycle of construction on the composition of the bilik. Secondly, further subdivision of the bilik family is done several years after the completion of the initial longhouse construction. Thirdly, the expansion to both sides of the longhouse will not occur if the upcoming construction of a new longhouse is near. At that time, the composition of bilik family expands and becomes more complicated.
