The chimney is constructed with mortar joints to keep the structure in place. As years go by, the mortar joints can begin to decay and create voids in areas of your chimney such as in between the bricks. This is typically the result of exposure to the elements, including the freeze and thaw cycle during brutal Irish winters.
If your chimney’s brick are in good shape, repointing might be the best option for you. This option helps repair the appearance, as well as, the structure of your chimney. It also prevents further damage and moisture from entering between the bricks. This is what can ultimately lead to your chimney experiencing major structural damage to the point where it needs rebuilding.