A vehicle interior trim component, such as a glove compartment or console door, and its method of fabrication includes an outer flexible shell having a peripheral contoured return flap captured within a peripheral gap provided between insert and backing panels of the component. Foam is injected into a space between the outer shell and insert panel and any gases and excess foam are allowed to escape from the foam space into an adjacent overflow chamber in a controlled manner through the gap while the return flap seals the assembly against external leakage of such excess foam.