Most chimneys are quite durable and can last years with few problems, but most older structures will need to eventually be repaired in some way. There are a few common issues requiring professional chimney repair, and if they are not fixed within a reasonable amount of time, they could cause multiple problems. A major chimney repair that never gets done could be the underlying cause of health problems for the home's residents, or can result in a small issue becoming much larger later on. For this reason, it is important to get to know the main types of chimney repair, such as replacing the liner, repairing mortar, and rebuilding from the ground up.
Many modern chimneys include a flue liner, which goes from the area where the fire is built all the way to the top of the structure. Its purpose is to keep any gases from leaking into the home, so a chimney with either no liner or one that is cracked can be a problem. Most masonry chimneys have liners made of clay, and when creosote builds up over time and causes a fire, the clay can get so hot that it cracks. To keep dangerous gases out of the house, a cracked liner should be replaced.
To keep a chimney looking its best and working well, it should be clear of cracks in the mortar. Most chimneys that are kept in the best shape are inspected annually and repaired as needed, since cracks in the mortar are quite common. Fortunately, they are usually easy to fix. One area to focus on is the firebox, which is where fires are built, so the mortar should be kept in the best shape possible. The top of the structure, or the mortar crown, should also be checked by chimney repair professionals to make sure there are no cracks.
Some chimney problems cannot be fixed with a simple repair, and require tearing down the structure and rebuilding it completely. For example, a severe crack at the top of the chimney near the crown will likely not require a complete rebuild, but one near the bottom may, especially in areas that are prone to earthquakes. Whether the crack is visible inside or outside the chimney, it may compromise the integrity of the structure enough to warrant a complete rebuild for safety reasons. Discussing all the alternatives with a chimney repair professional first is often the best move before tearing it down.