Slender beams subjected to compressive load are common in civil engineering. The rapid in-situ measurement of this stress may help preventing structural anomalies. In this article we describe the coupling mechanism between Highly Nonlinear Solitary Waves (HNSWs) propagating along a granular system in contact with a beam subjected to thermal stress. We evaluate the use of these waves to measure stress in thermally loaded structures and to estimate the neutral temperature, i.e. the temperature at which the stress is null. We investigate numerically and experimentally one and two L-shaped chains of spherical particles in contact with a prismatic beam subjected to heat. We find that certain features of the solitary waves are affected by the beam’s stress. In the future these findings may be used to develop a novel sensing system for the nondestructive prediction of neutral temperature and thermal buckling.