This work is devoted to the investigation of the influence of the embedding surfaces (substrates) on a spin crossover layer in the framework of a mechanoelastic model. We analyze how the properties of the spin crossover molecules (i.e. the thermal transition or the cluster spreading) situated inside a 2D layer are influenced by interactions between them and the inert molecules situated on two parallel surfaces, embedding the spin crossover layer. We conclude that the thermal transition is influenced both at the macroscopic scale (the shape and with of the hysteresis accompanying the thermal transition) and at the microscopic scale (formation of clusters) by the presence of epitaxial interactions with substrates. Equally, we analyse how the spin transition modulates the pressure exerted by the middle layer on the two substrates. The last part of the paper is devoted to the study of the possibility to induce the switching of the spin crossover molecules on the inner layer by heating the embedding surfaces.