The authors present results of vented explosion tests using stoichiometric propane-air mixtures in a room-size enclosure 63.7m3 in volume. The tests were focused on the effect of ignition location, vent size, and obstacles on explosion development and pressure buildup. The dependence of the maximum pressure generated on the experimental parameters was analyzed. It was found that the pressure maxima may be caused by pressure transients defined by the interplay of several factors, such as the maximum flame area and burning velocity in the chamber, and the overpressure generated by the external explosion. A simple model was proposed that allowed for the estimation of the maximum pressure for each of the main pressure transients. The model was found to agree with the experimental data within the experimental uncertainty.