Abstract The viability of preparing cellular ceramics suitable for external wall insulation of buildings was investigated using granite dust, ball clay, plantain peels, sodium silicate, and sodium hydroxide. The predetermined compositions of the raw materials were mixed homogeneously and then subjected to uniaxial pressing at 10 MPa. The formulated samples were oven-dried and sintered in a gas kiln at 850 °C for 3 h. The obtained cellular ceramics were then subjected to standard property tests. The results revealed water absorption of 19.5-41.7%, bulk density of 1.39-1.86 g/cm3, apparent porosity of 36.4-66.7%, thermal conductivity of 0.09-0.62 W/(m.K), and compressive strength of 0.9-18.4 MPa. From the results, the optimum sample of the cellular ceramics prepared is a potential thermal insulation material for load-bearing applications such as walling systems in buildings, where not only low thermal conductivity but also high mechanical strength is required.