I have to roughcast an extension built using block. I think I'm okay with applying a scratch-coat, but have heard that the roughcast topcoat itself can be applied either dry or wet. (It's going to be painted with white masonry paint so colour isn't an issue.) What's the easient way for a relative novice to get an accepatable roughcast finish? I have a few tonnes of crushed stone that I'm considering using as the aggregate as the larger particles match the size of existing roughcast on the older parts of the building. Would appreciate any advice.