A 3-D computational fluid dynamics model is used to estimate the thermal impact on structures exposed to fire in the urban interface. The burning of vegetation is represented by a well-adjusted gas burner diffusion flame. This article examines two situations, depending on which modes of heat transfer from the flame are considered. Model predictions reveal how the presence of the structure modifies the dynamic flow pattern, which in turn may cause the overattachment of the fire plume to the structure and then the enhancement of thermal impact. Numerical results, including flame geometry, are found to be consistent with experimental observations.