If the building is to resist high water pressure at the base, PVC Plastic Waterstops to be used in joints must be applied on the surface of the concrete that comes into conctact wiht water so as to avoid leakege of water through the joints. In no water pressure is in question at the base and it is intended to avoid transfer of dynamic motions along the joints, central type PVC Waterstops must be used at the centre of the cross-section of the concrete block.