Mortar Problems On Retaining Walls

Retaining walls are used throughout the landscape to hold raised garden beds in place or to secure slopes and terraces on the property. Brick walls are typically mortared in place, which makes them a strong and long-lasting option for retaining purposes. Over time, though, the mortar can suffer damage. Not only is this unattractive, but it can also lead to structural issues.

Mortar Damage Concerns

Retaining walls are meant to hold back soil and moisture. If the mortar begins to crack or crumble, that means moisture will make its way in between the bricks. When moisture freezes, it expands, which can break apart a retaining wall. The bricks themselves may even begin to crumble or chip more easily.

Even without freezing, the wall is weakened when the mortar is no longer present. Eventually, the weight behind the weakening wall will cause it to bow outward. If the wall is structurally important, as in it is holding in place a slope rather than a small garden bed, the slope itself may give way to erosive forces and collapse.

Common Causes

Age is the main reason that mortar begins to give out. As mortar ages, it begins to break down. This allows more moisture to make its way into the pores inside the mortar, which in turn causes the mortar to break down even more quickly.

Outside damages can speed the aging process. Sometimes this can happen at installation — a weak mortar mix will crumble more easily, for example. Damages can also occur if the mortar is pierced, such as with a nail, or chipped at, such as by using a weed trimmer up against the retaining wall.


Repair is the only option, as ignoring the problem will just lead to a wall collapse. Repointing, also called tuckpointing, is the method used to repair crumbling mortar. If the wall is otherwise in good condition with no bowing, the old mortar can be scraped out and new mortar can be installed. Although this is a painstaking process, it is much less expensive but just as effective as building a new wall.

For walls that have suffered bowing or brick damage, more involved masonry repairs are necessary. Supports must first be put in to hold the slope in place while the old bricks are taken down and a new wall is constructed. The good news is you can reuse the bricks if they are undamaged.

Contact an outdoor masonry service if you need more help with your retaining wall mortar.