These injections are always carried out with the aim of grouting and sealing the entire element cross-section. This is best achieved by ensuring that the drill hole remedial grouting crosses the joint roughly at the element centreline. As a rule of thumb, the required drill hole spacing should equal half the element thickness. The relevant drawings must be consulted in advance to establish the course of the joint, whether horizontal or vertical. Depending on the selected waterproofing system, any joint seals incorporated in the original construction may favour or hamper the success of the remedial works.