[Baz]

Rubber Trees (aka Ficus elastica) are extremely invasive and messy. They are notorious for having extensive root systems that seek out water and many times are responsible for clogged and/or broken water and/or sewer pipes.

The ideal scenario of course would be for the owner of the tree to contract a tree service to cut it down. If you have exhausted all efforts toward this, you could cut off all limbs overhanging your side and try to live with that situation.

There is a chemical that can be sprayed onto the open wound of a tree that translocates down into the roots and kills the whole thing. It's called Tordon RTU and is available from Amazon. You could spray this on all the open cuts left from trimming the limbs from your side and see what happens. If you spray enough surface area...it would do the tree in. Then at least it would stop growing.

If you're going to kill it by chemical means...this would be a better way to go than something environmentally damaging such as pouring diesel fuel on the roots as some might suggest.