Tree roots under foundations

Theoretically, it is possible. But the volume involved is usually relatively small - and "typical" grade beams can span across depressed areas of several feet. Of course, if the tree roots themselves involve a large volume that extends beneath tens of feet of grade beam, then you do have a problem.

Where are your sites located?

Question concerns continuous strip footings (common in our area). I realize grade beams are designed to span over, but with strip footings your "wiggle room" over discontinuities is much smaller. Just wondering if there is a relative size of roots where it might be a good idea to look into further.

FSS...most of the "dirt dobbers" in your area like to see anything 2" or larger in single occurrences (some of the more conservative ones even limit that to 1" or larger) or any accumulation of smaller roots (1/2" or above is a common limitation, though conservative)removed.

In sands this is more important than in more stable materials because of the raveling potential. The downside to this is localized cracking, but collapse potential is low.

Many variables lead this charge! The lower the root below the footing, the less problem. Leaving trees in place to grow next to footings usually does more damage (growth, water cycling) than removing the tree and leaving the dying roots.