Measuring movements and deflections in structural fire experiments can yield critical information to generate the knowledge required to further understanding of the behaviour of structural systems in fire. However, due to the influence of flames, smoke, and heat, detailed deflection measurements can be difficult to install and maintain during experiments involving fire or heat exposure. This paper describes the concept and functionality of a simple tracking mechanism for robust image analysis of structural elements heated from one side. The concept and its potential applications are demonstrated for a set of cross-laminated timber wall strips which were exposed to one-sided radiant heating whilst being subjected to sustained imposed loads. The deflected shape of the specimens was measured using a circle tracking technique, and the results then used to estimate and analyse the stresses within the wall strips’ cross-sections.