Due to recycling of scrapped tire rubbers and coconut fibers, a new building material composited of rubber particles, coconut fibers and cement is applied to building partitions. A lightweight coconut fiber/rubber cement board (LCRCB) consists of rubber/cement board as a sandwich layer and coconut fiber/cement as the matrix, where the sandwich layer containing three fractions of the rubber from 30% to 50%, and the matrix with a constant ratio of 15% coconut fibers in volume. Results show that the measured properties of LCRCB are found with water absorption between 13.8% and 15.4%, unit weight of 1400-1480 kgf/m3, bending strength of 1.97 MPa and coefficients of thermal conductivity in 0.261~0.286 kcal/m•oC•hr,. After the impact test, LCRCBs show no cracks, detachment, pinholes and the split on the impacted surface. Besides, LCRCB satisfies the 2nd degree requirements of incombustibility based on national standards. To be a building partition, LCRCB also shows no smoke toxicity in burning.