Yes, general advice would be not to plant a weeping willow (salix) close to a house, especially if you have a clay soil. I have been told that the roots can grow to be three times the height of the tree.

But I have also heard of the dwarf variety and hopefully this is what your neighbour has planted.

However, I too have a mature weeping willow in my back garden which I estimate to be around 40 years old. It is about 25ft from my house but I'm fairly comfortable with it because I'm on a sandstone soil. I have it regularly pruned so that it doesn't get too large and keep the surrounding ground wet during periods of drought.

When I purchased my property I originally considered felling it but am really pleased I didn't because it provides wonderful shade to sit under and is a delight to see and listen to in a summer breeze.