Get 1/2" or 5/8" particle board which ever you can afford or carry (it is very heavy). Stand up the boards on the common wall (1-2" from the base board). At the top, place 1" thick rubber foam, rolled up towel or cloth. So the top of the board is not in contact with the finished wall. The particle board can be painted or covered with cloth. I may fall in an earthquake, so prop furniture against it.