Ask Mr. Smarty Plants

We believe you are referring to the Fan-Tex ash tree; please read this previous Mr. Smarty Plants answer on what exactly that tree is. Since it is always a graft onto Fraxinus velutina (Arizona ash), we can only hope that reading our webpage and other information on that native plant would give some indication as to what the roots would do. One article that we read said that the mature tree was too large for residential use, which is not a good omen.

From Colorado State University, here is an article on Healthy Roots and Healthy Trees, We are not sure exactly what "near" is, but a mature tree with a large crown probably has roots growing from 2 to 3 times farther out than the visible crown. When roots come to an obstacle, such as concrete foundation, it will try to grow down below that obstacle, in search of water and nutrients in the soil. When it gets below the foundation, it will slurp out the moisture in the soil, the soil will subside, thus damaging the base for the foundation, and the foundation will crack. This situation is no different for a Fan-Tex than any other tree. You have to decide, which do you want? The tree or the foundation? If you can't plant your tree far enough away from the foundation to permit the tree roots to avoid the foundation then, yes, it is going to be a problem.