I'm redoing a bathroom and the walls are covered with plywood around the tub/shower. I need to finish the joints between the plywood above the tub surround and where it meets the sheetrock. Whoever did the initial work used sheetrock mud and it didn't seem to stick to the plywood very well, and I've been thinking of using water putty on the plywood joints and the mud only where the plywood joins the sheetrock. Any knowledge or suggestions?