With 80% of the exterior repaired it is time to tackle the roof. There is so much tar and dried glue that there are only two options. Replace the whole roof or put a 1/2" skim of plywood over the existing roof. I chose option two and will get to it as soon as I have prepared the front and back edges to accept rubber roof. Question: should I apply seam tape before or after I prime the wood for rubber compound.