Gelam wood (Melaleuca cajuputi Powell) which is widely used for substructure construction materials in South Kalimantan is classified into strong class II and durable wood class III. This study aims to provide more detailed information regarding what forms of use of gelam wood as substructure construction material and why gelam wood was chosen for it. This information will later be able to support the preparation of future utilization plans for the use of gelam wood considering that currently gelam wood is starting to decrease in availability. The method to identified the use of gelam wood as a substructure construction material is field survey method combine with other references. Gelam wood with a large diameter of 10-12 cm and a length of 4 m is generally used as a construction foundation for 1-storey building with an ultimate bearing capacity of 729,25 kg for single pile foundation. In terms of cost, the foundation with gelam wood material is cheaper than the mini-pile concrete foundation for the construction of the same building. The large size of gelam wood is also used as sheet pile or retaining wall with an average flexural strength of 100,13 MPa. The small size of gelam wood is generally used as wooden scaffolding where the cost of gelam wood scaffolding is 26.85% cheaper than iron scaffolding in the rental price, and 15 times the cost of the iron scaffold in the purchase price.