I am planning an addition/re-roofing to my home and thinking about going with a metal roof. The looks of the metal roof's along with the different color's really make the metal roof stand out. My question is the underlayment any different than a shingle roof? I was planning on 3/4 plywood for the addition, then a heavy felt paper then the standing seem metal roof. The re-roofing would be over the existing osb board after the shingles are removed. Some of the posts mentioned titanium as an underlayment? There was also mention of lathe strips? Do those have to be used on top of plywood/osb? or can metal be installed without the lathe strips? The attic has a good ventilation system and have never had any problems with it (25yrs.). I have really enjoyed the postings and comments from everyone. Thanks. dadzo from Pittsburg Pa.