We study the relaxation of a thermal grating in multilayer materials with interface thermal resistances. The analytical development allows for the numerical determination of this thermal property through the Approach to Equilibrium Molecular Dynamics and suggests an experimental setup for its measurement. Possible non-diffusive effects at the nanoscale are take into consideration by a non-local formulation of the heat equation. As a case study, we numerically apply the present approach to silicon grain boundary thermal resistance. (C) 2018 Elsevier Ltd. All rights reserved.