I have a wall in my bathroom back to a combination of brick and bare block prior to dot and dabbing plasterboard. After brushing down the surface is still very dusty and flaky.I have seen various posts suggesting that block walls should be pva'd or that a good soaking will be adequate before sticking the boards. Could somebody please tell me; if I do pva first is that the only preperation I need to do or would I still need to wet the wall prior to putting the dots of adhesive on. Sorry if this post sounds a bit silly. Thanks.