Despite intense research on building materials, the challenge of finding cheap and lightweight construction materials still persist for persons wishing to construct a house. A material that is getting attention of researchers and lightweight is Expanded Polystyrene (EPS). The aim of this study was to compare compressive strength and mass of blocks made when EPS were mixed randomly or in layered manner in cement-quarry dust mortar. The EPS wastes were placed randomly and in a single layer so as to give percentage volume of 0% (control), 10%, 20%, 30%, 40% and 50% EPS of the cube of 150 mm. The results showed that the average compressive strength of mortar was 18.67 ±1.33 N/mm2. The strength reduction proportionality factor for layered mixing was 0.76 to 1 and 0.29 to 1 for random mixing. This showed that reduction of strength was greater in random mixing than layered mixing. Increase of EPS above 30% randomly, resulted in lightweight blocks of between 1319 and 1669 Kg/m3, whereas increasing EPS in layered manner above 50% resulted in lightweight blocks of densities less than 1679 Kg/m3. This research showed that 40% EPS randomly mixing resulted in a light block which met the minimum strength criteria of 3.6 N/mm2.