Pretreated fibers are stiffer and tougher.Test results showed that the cement mortar mixed with oil palm fiber has lower porosity and water absorption than those with coconut coir fiber, but the density are higher because the density of oil palm fiber is higher than that of coconut coir fiber, and this affects the bulk density of the cement mortar and also other factors.It was found that the compressive strengths of cement mortarsmixed with oil palm fiber and coconut coir fiber to decrease with an increase in the fiber replacement ratios.Thermal conductivity of fiber cement mortars The results of thermal properties of the cement mortars as shown in Fig. 8 demonstrate that as the ratios of both fibers increased, the thermal conductivity coefficient reduced to 66% compared to control cement mortar.