The effect of house design variation on the completion time in a production building operation

In a competitive housing market, house builders customize their designs to attract more customers. This customization happens in the form of having various typical designs and allowing for limited variation in these designs. This variation affects the building process in different ways. This paper investigates the effect of this variation on the completion time of houses in a production building operation. For this purpose, a production building operation has been modelled and the launch of a new house type within an existing product line simulated. This simulation has been undertaken using two scenarios; one with the new type smaller than the current types and the other with the new type larger than the current types. The completion time of the houses in each of these scenarios showed that when the new type is smaller than the current types, its completion time fluctuates between its minimum completion time and the completion time of the largest type. It has also been demonstrated that in the case of the launch of a house type larger than the production types, queues in the production operation will be inevitable and the completion time of all types will grow infinitely. This research shows that in a production building operation a shorter completion time cannot be achieved by the introduction of smaller house types as long as the production is a mixture of smaller and larger types. In addition if production builders decide to allow for variation in their designs, the variation can create queues in the operation, and result in the completion time of different types never reaching their minimum level.