This study investigates the seismic response of an 11-storey reinforced concrete (RC) building subjected to vertical irregularities. Three types of vertical irregularities, namely stiffness, geometry and mass irregularities are considered and the seismic response in terms of storey displacement, storey shear and overturning moment are evaluated using response spectrum analysis for different seismic zones. The irregularities modelled in the building include non-uniform floor heights, uneven mass distribution by considering a swimming pool at 5th storey and variations in lateral stiffness, all of which can affect the building's dynamic behaviour during an earthquake. The primary objective is to evaluate and compare the structural performance of the building with a fixed base with ground motion records representing different seismic zones. The building is analysed using ETABS software and the seismic response is found out using Response spectrum analysis. In the present study, a G +10 storey building each storey has 3 m height and the total height of the building is 33 m. Stiffness irregularity is modelled by considering soft storey of 4.5 m height at base (SB), 4th storey (S4) and 7th storey (S7). For stiffness irregularity it is found that the base shear is more for regular model as compared to models with stiffness irregularities for all zones considered. Zone 5 exhibited the highest base shear among all zones. Geometric vertical irregularity is considered by reducing the dimensions of building at 3rd(G3), 6th(G2) and 9th(G1) floor respectively. It is observed that the seismic response viz base shear, roof displacement and overturning moment is higher for regular model as compared to vertical geometric irregular models for all zones considered. Considering mass irregularity (M5 model), it is observed that the seismic response viz base shear and overturning moment is higher for regular model as compared to irregular model whereas the roof displacement is maximum for irregular model for all zones considered.