I'm working on a place with some fun trees at the moment, two of which (both Scots pine) have significant lean. For one, the target in the lean direction is just fencing etc so no need to worry, the other has the potential to do damage.   The one that has the building built up to it has either grown well over 5cm in thickness in the last two years or is slowly falling. I reckon the way half of its root system is deprived of water may be an issue? If it falls I imagine the root plate will do