Terra cotta foundations predate to the late 1800’s and were used up until
the 40’s. Depending on the area, grade, and type of structure they are supporting, they can last as long as 75 years or more.
I suspect the terra cotta you speak of is commonly called structural terra cotta which can be a misnomer depending on its application.
While there are basically 4 categories of terra cotta, in the construction / building industry you would likely encounter either brownstone or fireproof.
As to the types of terra cotta… you are looking at dense, semi-porous and porous. Most exterior walls and foundations that are terra cotta typically will have either dense or semi-porous terra cotta.
You will find them both drystacked and at times mortared and may even find ribbed blocks which again may or may not have stucco on same.
Like any building component, you as a home inspector are more concerned with its condition at the time you inspected. Because it is brittle it is subject to cracking…when mortared in place, like any other masonry veneer the mortar then becomes an integral component of the foundation and must be inspected as well.
I personally would annotate in my report that it is a product that was commonly in use during the era in which the home was built however because it is a brittle product it should be inspected annually by a qualified specialists.
Hope that helps.