No the idea is to plaster the bags so that afterwards the walls look like conventional plastered walls. The fabric is not UV proof, so will degrade if left out in the sun for an extended period. Obviously the bags will be fine for months if not years if left unplastered, but it is advisable to plaster once you have the roof up. As an experiment I have a short screen wall made with some bags up on my balcony that have been up for about 6 months and they are still fine.