The stone ring was added after initial attempts to get plaster to stick well to anything we attached to the earth bags failed to produce something we felt was as sturdy as the rest of the house, and given that the rain was seen to splatter against the base of the house in a heavy storm, after much debate we ringed the base of the house in stones we sourced locally and with standard mortar for the level of durability we wanted. It was flashed with copper and then plaster applied over that, such that any water hitting the plaster and getting into it will travel down and get caught in the copper (which should be nearly immortal) and be directed out of the house.