This paper describes the application of a new global search technique, pgsl, that reduces structural costs for multi-storey timber housing. This technique is integrated within a computer aided design system that calculates production costs using a detailed product model. The cost calculation module was calibrated in collaboration with an industrial partner, and was tested on a full-scale completed project called winter city 2000 in sweden. It is found that the production cost for the shear-walls in the test case can be reduced by up to 10% due to an optimally directed search for structural designs. By using an explicit representation of the structural components in the shear-wall, it is also possible to increase the reliability of cost calculations.