Chimneys have a higher chance to sag or fall away from the rest of the house because at times they are not sitting on a full slab of support. This is especially true if the chimney was an addition to the house. If the concrete under the chimney is not as thick as the rest of the foundation, or it is not attached to the existing slab correctly, it makes it prone to slowly coming away from the home. There are many different precautionary methods during the actual construction of the home as well as after the construction of the home that one can take to ensure your chimney will always be intact.
The first thing to check is if where the edge of the chimney is apart of the main foundation of the home or if it was added on. Both situations will need different types of solutions to prevent you from losing your chimney and having to spend a lot of money in repairs. If connected to the main foundation slab, this means the concrete is thick below it and means you might have a bigger problem on your hand than expected. If it is a stand-alone foundation that is attached to the main foundation, this is a easy fix because of the small size of the concrete itself.
It is important to call out an assessor to investigate why your chimney is falling away from your home. They will know the right route to take in supporting it. When the main foundation is the problem, helical anchor systems can be used to find harder ground below your house to take pressure off the foundation itself. Your foundation will not work properly if it sits on soft soil. Pier driving heads can also be used in this situation. These sit on the edge of the slab and use a hydraulic jack system to level off the chimney.
If the slab itself was connected to the home after the construction, this means it is just seamed together with the main slab of your house. Because of this, using pier-driving heads can be very successful considering the load is light. If you use the hydraulic pump in excess while jacking the chimney up you could break the seam that connects the chimney slab to the foundation. You also have to watch out that you do not cause any damage during this process to the brick that is connected to exterior wall of the house while you jack the foundation up.