In-depth knowledge of the interaction effects of wood and preservative chemicals on surface adhesion characteristics is crucial for developing pathways to improve the adhesive bonding of treated woods. Therefore, this study investigated fundamental changes in the surface adhesion-related chemical characteristics of E. grandis sapwood and heartwood impregnated with copper azole (CA) and disodium octaborate tetrahydrate (DOT) wood preservatives. The characterization techniques employed include scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy and Fourier transformed infrared spectroscopy. The results obtained revealed that CA and DOT impregnations significantly altered the acidity and reduced the polar functional groups on E. grandis sapwood and heartwood surfaces. The effect was more pronounced with DOT impregnation and on the sapwood. The observed modifications signal that the CA- and DOT-treated wood adhesion could be inhibited due to reduced opportunity for chemical bonding between the treated wood and adhesive molecules. Furthermore, there is a high likelihood of the hindrance of adhesion via mechanical interlocking as a result of chemical deposits, particularly in copper azole-impregnated wood. Considering the observed changes in the surface chemical characteristics of the CA and DOT-impregnated E. grandis, adhesive compatibility and adapting bonding parameters, such as assembly time and bonding pressure could be vital in ensuring adequate bonding of the treated E. grandis wood.