Most problems with brick sidings occur along the mortar joints; you’ll find that you seldom have problems with the bricks themselves. If mortar is poorly applied or contains substandard ingredients, it will eventually crumble. Even the best mortar wears away eventually: The mortar shrinks and cracks open. Freeze-thaw cycles in cold-winter climates, heavy rain, settling, and earthquakes also result in mortar problems.

Heavy rain and dampness can also cause brick to lose its effectiveness as insulation and may eventually affect the finish of interior surfaces. The fix for this is to “repoint“ the brick, which means to remove some of the mortar and apply new mortar to the joints. Here’s how to do it:

1) Buy dry weather-resistant Type N ready- mixed mortar at your home improvement center and mix it according to the label directions.

2) Using a cold chisel and hammer, chip out the crumbling mortar to a depth of 1/2 inch and then brush the joint vigorously with a wire brush.

3) Dampen the cleared joints to accept the new mortar, and, using a small trowel, pack the new mortar into the joints as shown below left. Tamp the mortar with the flat of the trowel.

4) You should match the finish of the mortar joints to the existing joints. Allow the mortar to set up until it’s somewhat firm and then finish the joint by drawing a jointer (or similar tool) along it, as shown below right. Most often, the object is to give the joint a slightly concave profile.

5) Remove excess mortar from the surface of the brick using a clean trowel.

6) Allow the mortar to set up. and then sweep it with a stiff brush.

7) Use a damp rag or sponge to keep the mortar joints moist for about four days. This ensures that the mortar will cure properly so that it doesn’t crack again.