Chimneys extend high above the roofline where they have very little protection from the elements. Due to this fact, there is a high likelihood that your chimney will need brick repair at one point or another. Repairing brick by yourself is not an impossible task and with the right tools and information, you can turn a repair that would be expensive to pay a professional to do into an at home project to save money.
Brick match is an important part of the process. Be sure to take an actual brick sample to a brickyard when you are matching brick to the project. One out of place brick can make the repair look very tacky. You may also want to consider purchasing mortar pigment if the mortar you have purchased does not match your existing mortar.
You need to get the damaged brick out first. Make sure that you do not damage any of the other bricks in this process. Use a chisel and a hammer to remove the damaged brick one piece at a time. Remember, safety first. Always wear eye coverings to prevent a chunk of air borne brick from hurting you. Chisel out the mortar from the hole the brick left behind and clean out the opening with a brush and rinse with water. This is a very necessary step toward making the repair last as long as possible.
After mixing your mortar and adding in any necessary pigments, trowel the mortar into the hole on the bottom and both sides. Wet the brick slightly so it will take the mortar better. Make the mortar about ¾” thick on the bottom and both sides of the hole. Apply more mortar to the top and sides of the brick and place the brick in the chimney until it is even with the others. Mortar will ooze out during this process. Be sure to remove this mortar from the face of the brick to prevent staining. Do this by waiting until the mortar is nearly dry and wire brushing away any extra mortar. Also, make sure the mortar is flush with the face of the brick by either removing some or adding more in with a pointing tool.
Seal your repair after with a penetrating water repellent. A water repellent is necessary to making your repairs last longer and will prevent new needed repairs from surfacing. Water is often the culprit to chimney brick problems, so protecting your chimney is a very necessary step in the process.