we are about to buy a house with a weeping willow 7 meters from the house. I am getting such conflicting advice re subsidence, heave, drains etc. Surveyor thinks it is OK, insurance company is OK about it. house is 100 years old and tree is 50 years old but has been kept well trimmed. OK to proceed ???
Just keep the tree small and the roots will stay small, remember you can cut or do anything you like to a willow, completely cut the trunk in half if you want it will still grow without any problems. Even if you fell the tree it will just come back again if you dont poison the roots.
If it's been there 50 years it shouldn't be a problem. Willows take a lot of water from the ground. The main problem comes from killing them or removing them. The soil will become wetter and expand, this causes heave and can create structural problems. Keep it well trimmed and stop worrying. The Insurance company are aware of it and have taken on the risk.