Tuckpointing in the Seattle Area, WA.

Mortar is meant to be the softest thing in a masonry wall. The wall moves – thermally, seasonally, under load – and the joint absorbs that movement so the units do not have to. It also acts as the wall’s release valve for moisture. That means mortar has a service life and brick largely does not, and after several decades the joints on a Puget Sound house will be eroded, crumbling under a key, or recessed deep enough to hold standing water against the brick.

Once the joints open, the wall stops being a wall and becomes a collection of bricks. Water runs in behind the face, saturates the units, freezes, and starts spalling them. On a chimney it reaches the flue; on a wall it reaches the framing. The brick you are trying to protect gets destroyed by the joints you did not maintain, which is why tuckpointing at the right moment is the cheapest masonry work there is, and why leaving it is the most expensive.

Doing it properly means cutting the joint back to sound mortar – typically to a depth of about twice the joint width, not scraping the surface – cleaning the cut, and filling it in layers with a mortar matched to the original in strength, colour and texture. The strength match is not optional. A modern portland-rich mix is harder than the brick around it, and a joint harder than its units transfers movement into the brick and cracks it. Most of the badly damaged brick we are called to repair was damaged by a previous repointing job.