Industries related to the acquiring of building materials may soon face a shortage of natural resources and an associated increase in costs of their acquisition. Therefore, it is necessary to look for possible ways to reduce the exploitation of natural resources and instead use recycled raw materials. Such policies fit into one of the most important trends in modern construction, which is sustainable development. In the conducted research, the Taguchi method was utilized in order to investigate the impact of modifying cement mortars with rubber and cork waste on the selected properties of the obtained composites. Thanks to the above method, we managed to obtain the desired information about mortars in a shorter time and at a lower cost than using traditional testing methods. Using the selection in planning method, we confirmed that rubber waste can be a good substitute for sand in mortars.