well the roots of a plant sometimes are twice as long so the root may be 1 meter long or slightly more as after all it is a tree.

They normally can be reckoned to spread out to about the width of the branches. For Sorbus the recommended planting distance from buildings is 7 metres. The danger is not so much the roots disturbing the foundations so much as the effect of shrinkage and expansion in varying weather conditions - this is much more serious in clay soils than light ones. You can Google "Trees minimum planting distances buildings" and get lots of information. A garden wall wouldn't matter nearly as much as a house wall but even with a garden wall it would have been better a bit further away.
Bear in mind also that it will overhang neighbouring land which may not be welcomed by the owner.