Plate and frame heat exchangers are frequently installed in processes where the formation of deposits on the heat transfer surface cannot be avoided. To make provision for fouling, most plate heat exchangers (PHE) are overdesigned in terms of excess heat transfer area. In PHEs, adding extra parallel plates usually provides this excess area. This study investigates different means of adding heat transfer area to find the optimum strategy. The overall effect on heat transfer and fouling is investigated, when this excess area is provided in three different ways, resulting in configurations with different sizes, shapes of the plates and/or flow arrangements. These results lead to design recommendations, which are presented.