On 21/05/17 00:06, earthstick wrote:
Is it true that Wisteria can grow underneath foundations and cause them to lift? How far do the roots travel?

Depends on who you want to believe. No doubt you've already Googled
"wisteria" and "subsidence", and come up with numerous hits.

The problem is that once one mention is made, this is repeated by others
without any checking. You will find many mentions of wisteria,
pyracantha, and even roses(!) as shrubs which could cause damage to
walls. But as Chris pointed out, wisteria have been grown against house
walls for years without apparent problem.

About 9 years ago there was apparently a legal battle between Nigel
Kennedy and his neighbours over a wisteria growing against his house
which was said to be damaging the neighbouring house's foundations
(http://www.dailymail.co.uk/tvshowbiz...wisteria.html).
Seems strange to me that it wasn't damaging Kennedy's house, but there
you go. So how was it resolved? Who knows? All I can find is a sideways
reference two years later in another newspaper article
(http://www.independent.co.uk/news/pe...h-1980487.html)
which referred to "Nigel Kennedy's pretty, wisteria-hung cottage in St
John's Wood". That suggests to me the wisteria was not cut down.

Then there is this learned article:
http://www.theclayresearchgroup.org/...%20Edition.pdf
which suggests that a wisteria was the main cause of damage to a
property in London:-
"The initial distortion survey suggests the shrubs growing against the
wall may have contributed significantly and our recommendation is that
they be removed whilst precise
levelling continues over the next twelve months to determine if nearby
trees are also making a contribution."

The problem is that the Clay Research Group have numerous follow-up
articles about Aldenham, and, as far as I can see, *none* mention the
wisteria again, but do mention a large willow!

I have a fairly large wisteria growing less than a metre from my house.
The property was underpinned over 20 years ago due to subsidence (due to
inadequate foundations). Reading through the documentation, some trees
were mentioned, but never the wisteria (maybe it was planted after the
underpinning, or was very small at the time). The point I am trying to
make is that if anyone looked at a possible "subsidence" problem today,
would a finger be pointed at the wisteria, even though there was no
evidence for it?

--

Jeff