This article presents an investigation of the properties of natural fiber based composite building materials
that is applicable for hot and humid climatic regions. These materials were made of cement mortar
containing coconut coir fiber and oil palm fiber, both waste products from agricultural manufacturing
in Thailand. They are intended to be used as roof sheet and siding to reduce heat transfer through buildings
and energy conservation. The investigation focused mainly on the effects of both cellulose fibers on
the physical, mechanical and thermal properties of products. Test results showed that increasing the percentage
replacement of natural fibers tends to reduce the density, compressive strength and flexural
strength of the materials. Fiber cement products mixed with coconut fiber yielded lower density than
that of oil palm fiber. The mixtures of fiber cement products containing up to 15% of both natural fibers
by weight of binder yielded the acceptable physical and mechanical properties. Furthermore, the thermal
conductivity of the natural fiber cement sheets was 60% less than that of the control specimen. The
results of this research can be used as a guideline for using agricultural residues to develop fiber cement
products for residential building applications.