Afraid to tackle cracked bricks? Dye some mortar for a durable and invisible repair.
Synopsis: Bricks and mortar crack with time. In this article, veteran mason John Carroll delves into the tools and techniques for repairing damaged brick masonry, including how to match the colors of new material to old, the type of mortar to use, and how to repair a brick without replacing it.
Editor’s note: This article was written before OSHA released their guideline about the dangers of breathing in silica dust when cutting or grinding masonry. Be sure to protect yourself, your coworkers, and your clients if you take on a project like this.
There are a lot of reasons people choose brick for a building material. It doesn’t provide an endless buffet for termites or serve as a building site for carpenter ants. Woodpeckers do not delight in drilling holes in it. It’s dimensionally stable, doesn’t rot or burn, and never needs to be painted. With all these things going for it, though, brick has an Achilles heel: It’s hard and inflexible, and it cracks under certain conditions.
Whether the cracks are caused by movement, insufficiently filled joints, or simply too many decades of being exposed to the weather, the owners of brick houses in Durham, N.C., often call me to fix them. The reason they call me is because I do more than slop mortar into the cracks. I make an effort to match the color of the existing mortar, and when bricks are cracked, I repair the cracks with mortar dyed to match the color of the bricks. I also prep the surface properly, use the correct mortar, and keep the joints as neat as possible. After packing the joints with mortar, I tool them to match the profile of the joints on the rest of the wall. My goal is always to make the cracks disappear.
Why brick cracks
Masonry structures crack for several reasons. The first is because the footing or slab the masonry rests on moves. (Many older houses don’t even have what we’d consider footings today; the structural brick wall rests directly on the soil.) The first building material is not the footing but the soil that it bears on. Footings should be placed on virgin soil or soil that has been mechanically compacted to reach the proper bearing capacity.
Water can cause some otherwise sound soils to become soft and plastic, reducing their bearing capacity and resulting in differential settlement that cracks the footing. Saturated soil that freezes can push sections of a footing up, or it can push laterally on a below-grade masonry wall. Another problem is that structures such as foundation walls and retaining walls are often underbuilt. Masonry that’s subjected to strong lateral forces, such as those imposed by soil, should be reinforced with steel.
A well-planned system to drain water away from the foundation is essential. But the work of even the most careful builder can be undone later by changes to the grade around the house. Landscaping that piles up mulch and dirt a few feet from the house often holds water that soaks in and eventually causes cracks in footings and concrete slabs.
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