Walls and trees can remain friends, even when they cross paths.
Build a bridge in the wall, rather than cutting any any roots below the foundation.
That way it leaves roots room to move, and the tree stays healthy. Even over time the wall is not damaged by any heaving action of the roots either.
A lintel stone straddling a gap where the root is, cleverly leaves room, with a view to allowing the exposed tree root to grow.
