The message
from (Mike Lyle) contains these words:

I'd love to hear from a structural engineer or similar authority on
this question of tree-roots and house foundations. I imagine, quite
likely wrongly, that modern concrete footings must be too tough a nut
for the roots actually to damage. But would a really vigorous root
system, in time, alter the subsoil conditions so that prolonged
passages of extreme weather (or over-extraction from the water-table)
could result in subsidence even with modern building practices?

Don't you believe it. The roots grow and in effect, use hydraulic power
to do so. Have you never seen a mushroom pushing up through a tarmac
pavement? They will even lift paving stones.

On the other hand, old country houses in some places may hardly have
foundations at all: I had a Welsh farmhouse which seemed to be
balanced on no more than a few strategically-placed big stones on
boulder clay. It was remarkably sound; but I could easily guess at the
damage a good weeping willow might have done.

My parents' house was built on a foundation of willow twigs, probably
more than four hundred years ago.

Drains are a different story, of course.

No, just a different chapter of the same story.

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