We're remodelling a bathroom. Lath and plaster walls come almost to the corners of the fiberglass tub/shower surround. Thought about tiling above the tub surround, using vapor barrier/duroc/thinset/tile..but I don't want to tile the side corners between the lath and plaster wall and the tub surround. Can I lap duroc over the side flange of the tub /shower surround and skim coat, then paint, then caulk duroc/fibergalss gap? What mud would I use for this? How would I join the lath and plaster to the duroc? I know how to handle greenboard, but in our other bath, it requires a lot of maintenance so I was thinking the plastered Duroc might be easier in the long run. What do you think?