This study investigated the effects of wolframite on the fire resistance and adhesion strength of intumescent fire-retardant coating (IFRC) using a siloxane-modified epoxy binder. The modification of bisphenol A epoxy was confirmed via Hydrogen-Nuclear Magnetic Resonance Analysis. The IFRC samples were developed with wolframite (0.25�2.0 wt) and evaluated for Thermogravimetric analysis (TGA), fire resistance test, furnace fire test for char expansion, morphology and chemical composition, adhesion test and water immersion test. This study identified a coating formulation containing 2.0 wt of wolframite that showed 57.2 improvement in the residual weight, substrate temperature of 176.7°C and produced a compact char. Field Emission Scanning Electron Microscopy showed that the addition of wolframite reduced pore size thereby increasing the char strength. X-ray diffraction identified iron neodymium compounds in the char layers, which lowered the pore size resulting in lower substrate temperature. X-ray photoelectron spectroscopy indicated that the antioxidant capability and the carbon content were increased by 6.9 and 50.3 respectively. The adhesion strength was reduced, however, was within the industrial standards of 2.07 MPa. The water immersion test showed a maximum 66.7 reduction (WF2.0) in the water permeation through the coating. © 2024 John Wiley & Sons Ltd.