This paper shows the results obtained for the variation of the mechanical properties of adobe units subjected to simulated environmental factors of radiation and condensation. For doing this, adobes over three hundred years old, taken from the Chapel Doctrina de Tausa, and new laboratory-built adobes were studied. Both kinds of adobe blocks were subjected to alternating cycles of 6 hours of UVA radiation and 2 hours of condensation for consecutive periods of 360, 720, 1440, 2160 and 2880 hours of exposure. At the end of each period, the change in mechanical properties of the adobes was analyzed by means of stress-strain tests. It was possible to conclude that the exposure to UVA radiation accelerates the variation in the mechanical properties of the new adobe blocks, while for the old Tausa-Chapel blocks it has no perceptible mechanical effect. Also, it was established that the changes in adobe resistance are given by the variability of cohesion, as the friction angle of this material does not change with time.