hello, if you want to kill the whole ivy the best way that i was shown years ago when i had a large over grown ivy was to find the main roots where they appear from out of the soil (i had about seven of them) and with a hacksaw cut them as close to the soil as possible, then force the cut apart and jam something between them to stop the cut parts going back on top of each other,it took a full growing season and winter for it to fully die but this ivy completly covered a double garage,as for the roots in the soil they never regenerated and i dug as much as i could out, hope this helps,