Brick and Block Foundations


Bricks, at one time, were used extensively to construct foundations. Today, however, if a foundation doesn't consist of concrete, it is probably constructed of concrete block. In either case, brick and block have one thing in common. They are both joined together using mortar, a combination of sand and cement. 

Unfortunately, over time, the mortar tends to deteriorate. Cracked and deteriorating mortar joints are not only unsightly, they also diminish the integrity of the surface and can allow water to get behind the brick or block causing major damage. This can be avoided by tuckpointing the brick or block foundation, which means the removal and replacement of cracked or missing mortar. 

If the cracked or deteriorating mortar is extensive (an entire foundation, wall, or wainscot), tuckpointing is a project that is best left to professionals.

If the area is manageable, the task can easily be performed by a do-it-yourselfer by following these steps:

  • Chip away cracked and loose mortar using a slim cold chisel and a hammer. Remove the existing material to a depth of approximately 1/2inch. 

Be sure to wear safety goggles to avoid catching a piece of flying mortar in the eye. Use the cold chisel slowly and carefully to avoid damaging the surrounding brick. Clean up all of the loose material and dust using a brush after you finish chiseling.

  • Prepare your mortar and allow the mix to set up for about 5 minutes.

Mortar can be purchased pre-mixed, or you can create your own batch using 1 part masonry cement and 3 parts fine sand. In either case, you want to add enough water to create a paste -- about the consistency of oatmeal. It's best to keep the mix a touch on the dry side. If it is too runny, it will be weak and will run down the wall, making it difficult to apply.

  • Brush the joints with fresh water.

Doing so removes any remaining dust and prevents the existing mortar from drawing all of the moisture out of the new mortar. Otherwise, the mortar can be difficult to apply and will most likely crack.

  • Apply the mortar using a pie-shaped trowel called a "pointing trowel."

Force the mortar into the vertical joints first and remove the excess (to align with the existing adjacent mortar) using a brick jointer. The brick jointer helps create a smooth and uniform finish. After all of the vertical joints are filled in, tackle the horizontal ones. Avoid applying mortar in extreme weather conditions because the mortar won't properly set up.

  • In a week or two after the mortar has had the opportunity to set up, apply a coat of high-quality acrylic or silicone masonry sealer.

The entire surface (brick, block, and mortar) should be sealed. The sealer prevents water damage, which is especially important if you live in an area that gets particularly cold. Unsealed brick, block, and mortar absorb water that freezes in cold weather. The water turns to ice and causes the material to expand and crack. Periodic sealing prevents this from occurring.