In traditionally built rubble stone walling it should be expected that the mortar that was used in its original construction will deteriorate over time and a need for repointing will eventually occur. If the wall was correctly built in the first place this is only liable to be required some time after the first 100 years. If repointed properly a further century of life can readily be expected from the wall without much additional maintenance. Over the last few decades the processes involved in doing this work effectively have not been fully understood. As a result, much superficial and inappropriate work has been carried out that will not last as long and will soon have to be redone. This INFORM aims to guide building owners through the steps that are required for contractors to carry out repointing work properly.