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Background

  • I have recently moved into a house.
  • There is a willow tree on the property (not sure which type).
  • The willow tree is is approximatly 5 meters from the house foundation.
  • The house foundation is a "suspended foundation".
  • The tree is about as old as the house, around 8 years.

The question: Does this tree pose a threat to the house? I have been told by several people that the tree can go under the house and lift the foundation resulting in expensive repairs. If this is the case, is there an immediate danger, or how big does the tree need to be before we need to concern ourselves with this.

The tree in question: enter image description here

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I'd be uncomfortable about a tree that close to the house unless I knew precisely which variety it was and it was a small tree, say no more than 4 metres tall with a similar spread. Even that means branches may later scrape against the upper parts of the house though. I note that the tree is tending to lean away from the house already, in an attempt to head for more light. Willows in particular do like a lot of water, and have a tendency to infiltrate any sources of water such as drains and pipes, especially if drought occurs regularly.

In terms of subsidence or a threat to the house foundations, that's usually only a major threat on clay soils, but I wouldn't plant any Willow within 12 metres of a structure with foundations of any sort, even on non clay soil. Some more reading here which might help you decide https://www.rhs.org.uk/advice/profile?pid=225 but otherwise, consult a reliable tree surgeon or arborist for their opinion.

UPDATE:

You've said your soil is clay, which means I'd recommend removing it - if you want something there to replace it, a taller shrub/small tree such as one of the Amelanchiers would be safer. Amelanchier 'Obelisk' for instance is quite narrow and won't be bumping into the upper parts of the house, but note that Amelanchier does not like limy soil.

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  • The soil is clay. I have no problem trimming the tree so its really only the roots im worried about, – JensB Mar 11 '18 at 15:32
  • I'd remove it if your soil is clay and choose a large shrub instead, if you particularly want something there - root spread can be unpredictable, and Willow roots will head for damp or wet soil. Which might be under your house in summer... – Bamboo Mar 11 '18 at 15:34
  • Ok. Thank you. Really like it so it’s kind of sad to cut it down, but better it than the house :) – JensB Mar 11 '18 at 15:51
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    Shame its a Willow.. you might have got away with one of the smaller Birches, but look on it as an opportunity to plant something else! – Bamboo Mar 11 '18 at 15:57
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    I agree with the general warnings of Willow roots. They will find cracks and seams, infiltrate them, then grow within them and widen the gaps. On the other hand, a gardener’s solution would be to coppice that trunk and harvest it yearly. This greatly reduces the tree’s root system. The wood harvested is always useful for garden use. – herb guy Mar 11 '18 at 19:36

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