Butt joints between cross-laminated timber (CLT) panels play a decisive role in the global stiffness, load distribution , and robustness of CLT floor systems. Experimental studies have shown that joint detailing strongly affects serviceability response and moment transfer capacity, particularly for panel-to-panel connections in the minor strength axis [1]. However, many current modelling approaches for CLT butt joints rely on linear connector idealisations, motivating the development of formulations that can represent coupled withdrawal–embedment behaviour and stiffness evolution for the derivation of slip curves of the joints for structural analysis. This paper presents a numerical modelling framework for CLT butt joints based on a beam-on-foundation (BoF) formulation. A three-dimensional finite element model is developed in Abaqus to analyse butt joints assembled with inclined, fully threaded screws. Each screw is modelled as a beam element supported by a distributed elastic foundation representing the surrounding timber, following established BoF concepts for dowel-type fasteners in CLT [2]. The foundation is decomposed into axial springs governing withdrawal behaviour and lateral springs governing embedment behaviour, with stiffness assigned at the level of individual CLT layers and aligned with local material orientation. This formulation enables explicit representation of the coupled shear–withdrawal mechanism and frictional effects observed for inclined screws. Nonlinear axial and lateral spring laws are introduced to capture stiffness degradation and force redistribution as embedment and withdrawal mechanisms evolve. Timber–timber contact at the joint interface is modelled using nonlinear contact with friction. The model is applied to butt joints subjected to various types of loading, considering both major and minor panel directions. Model calibration and qualitative validation are performed against experimental results reported for CLT panel-to-panel floor joints and moment-resisting CLT connections [1]. The simulations reproduce serviceability-limit-state stiffness and capture the onset of nonlinearity associated with early ultimate-limit-state mechanisms. The results demonstrate that the BoF methodology provides a transparent and computationally efficient basis for extracting stiffness and early strength indicators in CLT butt joints. Butt joints between cross-laminated timber (CLT) panels play a decisive role in the global stiffness, load di