Tuckpointing and repointing in Mobile

Mortar is the soft part of a brick wall on purpose. It takes the movement and the weather so the brick does not have to. Over enough years it gives up. The surface turns sandy, the joints sink back behind the face of the brick, and in places the mortar falls out completely.

In Mobile, rain does most of that work. It rains hard and often here, and storms off the Gulf drive water sideways into the face of a wall. Every joint that has opened up takes some of it in. Once water gets behind the face, the brick stays wet longer, salts come out white on the surface, and loose brick is not far behind.

Walk the house and look close at the mortar, especially on the side that takes the weather and down near the ground.

• Mortar that turns to sand when you scratch it with a key
• Joints sunk back from the face of the brick
• Holes and gaps where mortar has fallen out
• Hairline cracks running along the joints
• White salt stains or damp patches that keep coming back in the same place

The old mortar gets cut out of the joints to a good depth, with a grinder or by hand depending on the brick. Soft old brick calls for more hand work so the edges do not get chipped. The joints are cleaned of dust and dampened. New mortar goes in, packed in layers until the joint is full, and then it is tooled to match the shape of the joints around it.

People use tuckpointing and repointing to mean the same job, and most of the time that is fine. Strictly speaking, tuckpointing is an older method that adds a thin line of contrasting mortar to make the joints look crisp. What most houses need is plain repointing, with the bad mortar out and good mortar in.

A lot of older Mobile brick, the kind on houses in Oakleigh, Old Dauphin Way, Midtown and downtown, is soft and was laid in lime mortar. Lime mortar is softer than modern cement mortar and lets the wall breathe, so moisture can dry out through the joints.

Packing hard modern mortar into a wall like that is one of the most common mistakes made on old brick. The joint ends up harder than the brick beside it. Water can no longer leave through the mortar, so it leaves through the brick, and the brick edges and faces break down. The right mortar for old brick is one that is softer than the brick it sits in. Newer brick on later houses can take a stronger mix.

If the house is in one of Mobile's local historic districts, ask the City of Mobile about review before work on the outside starts.

New mortar is mixed and tinted to come as close as it can to the old joints. Old mortar has weathered for a long time and picked up dirt and stain, so the color to match is the one under the surface, on a joint scratched clean. Fresh mortar always looks a little lighter when it goes in and settles down as it weathers.

Not every wall has to be repointed at once. On a lot of houses the joints on the weather side, the chimney and the bottom courses wear out well before the rest. Repointing those first is a sensible way to spend the money, as long as the rest of the wall gets watched. Donald will tell you what he sees and what can wait.