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Madison, Wisconsin. Efflorescence can be found on all types of masonry walls - here the efflorescence is evident on the brick surface below the window. Source: Photographer Mark Fay.

If your historic house or building was built before 1930, it could have a brick foundation. Brick foundations were used during all periods of historic house construction in Wisconsin through the 1920s. You might be able to solve some of the typical problems you will face with your brick foundation on your own, while other problems will require the expertise of a professional mason.

The Nature of Historic Bricks

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A brick foundation wall that is bowing inward along its length and height. Source: Bob Yapp

Bricks are smaller than stones and vary in their hardness. Bricks are made from wet clay and then fired in brick kilns to cure them and make them harder. All fired bricks have a harder outside surface than inside. The kiln firing process varied over time as technology changed and improved, and some early bricks were not fired as well as later bricks. By the late 1800s, bricks were much harder than the earlier versions. These harder bricks were structurally stronger, less prone to moisture damage, and could handle harder mortar with Portland cement.

Bricks laid after 1900 are harder and not as easily scratched as bricks laid before 1900. You can determine the hardness of your bricks by using a small screwdriver to scratch the surface of your bricks. Use medium hand pressure to scratch the face of several bricks in an out-of-the-way area: 

• If your bricks show almost no sign of scratching, you have hard-fired bricks.
• If your bricks show no more than a surface mark, you have medium-fired bricks.
• If your bricks show scratches that are 1/16-inch deep, you have soft-fired bricks.

Early brick foundations were laid using soft, lime-based mortars. Starting in the 1890s, the lime mortars used in brick foundations may have had small amounts of Portland cement added to them. The Portland cement allowed faster and harder curing for use with the newer, harder bricks.

Typical Brick Foundation Problems

You may want to hire a preservation masonry professional to identify the cause of any problems you are having with your brick foundation. The most common problems you are likely to encounter with your brick foundation are discussed below. Click the link on each subject to learn how to solve the problem.