There is a 80-ft tall douglas fir tree three feet from my outside wall and
it has been there ever since the house was built some 20 years ago. I
recently read that roots of large tree could damage house foundation.
However, nobody else (including an arborist, a house inspector) who saw that
tree ever mentioned anything like that, although I didn't specifically ask
them about this issue.

On the other hand, my driveway was cracked by a much smaller tree (maple)
which forced me to cut it down. So "large tree roots may damage house
foundation" does have a ring of truth. On the third hand, if that was true,
the builder (and a reputable one) wouldn't have built the house 3 feet away
from that tree, would they?

Any thoughts?