We use pieces of wood cut the width of the open space between the washer/dryer/refrigerator and the wall, high enough (so they can't jump over) and attach it to the wall with metal angle brackets. This blocks their access from getting behind the appliances. I know this is a better idea for home owners than apartment dwellers, but it keeps the munchkins out and safe. Mary and the 11 Munchkins [Posted in FML issue 2750]