Foundation cracks can't be ignored, as structural damage to the home can result if the cracks spread. You can also end up with a water problem in the basement, as well as other issues. The first thing you need to do is determine what type of foundation you have and then address the situation accordingly.
Cast Concrete Foundation
A cast concrete foundation is a type found in most homes. Concrete is a mixture of sandstone and cement that provides strength and a solid base on which to build. The most common cause of cracks appearing in the foundation is settling. After a new foundation is laid and the new home is subsequently built upon the foundation, the foundation will “settle” into the surrounding earth. These types of cracks are usually minor, but should still be repaired to prevent foundation cracks from developing into a problem later. Attention must be paid to the moisture content of the concrete while it is setting, as lack of moisture can also cause cracks. There are several ways you can address these cracks. Most cracks can be repaired from the outside of the building. The visible crack is not the problem and the cause of the crack needs to be determined. It could be that subsidence in the soil is the cause, but if a wall is actually moving, then the reason for the movement needs to be known and addressed.
If water is seeping into the basement through the foundation cracks, you need to find the source of the leak and repair that area first. The leaking water needs to be led away from the house before the crack and surrounding area can be repaired. If gutters are broken they need to be fixed first. Check the slope of the ground around the house to make sure that the drainage isn’t blocked. Allow it to dry out before attempting to repair the foundation cracks.
Using an Injection of Polyurethane
Polyurethane is one material used to fill the foundation cracks by injecting it into the area where it swells and dries. It is long-lasting. Because it is injected it gets into the hidden cracks as well,
Applications on the Exterior Skin
Modern technology has developed to include products manufactured for application to the exterior skin of the foundation. While this will not help with a moving foundation, it will prevent the cracks that are allowing damp into the home from expanding and allowing in water.
Bitumen Damp Proofing
The old tried and true use of bitumen onto the walls still applies, although modern methods have updated this to a form of rubber sheeting that can be adhered to the walls. Since it is applied as one single continuous sheet and stuck onto the walls, dampness will not penetrate it. It can be taken above ground level to stop water seeping in from above. It is still important to make sure that the drainage of the water around your home leads water away from the house.
A moving foundation is a very serious problem that requires an expert's help in repairing these structural problems that will require a lot of work.