Important limits on the information provided here
The information on this website is provided for general educational purposes. It isn't professional engineering advice and must not be treated as a substitute for an assessment of your property by a qualified person.
Foundation problems vary enormously between properties, even between neighbouring houses built at the same time. Soil conditions, drainage, construction methods, and the history of the site all change what's happening and what should be done about it. A description on a web page can't account for any of that.
Where a foundation issue may affect the structure of a building, the appropriate step is an assessment by a licensed structural engineer. Nothing on this site should discourage anyone from obtaining one, and several pages actively recommend it.
Photographs and diagrams on this site are illustrative. They aren't photographs of work performed at any specific property and shouldn't be read as representing a particular job, result, or condition.
Any timeframes, methods, or outcomes described are general. They aren't a guarantee, a warranty, or a representation about what will happen at your property.
Do not delay seeking a professional opinion because of anything read here. If you believe a building may be unsafe, contact a qualified professional or your local building department without waiting.