I recently purchased a single story duplex built in 1951. It needs a new roof. I would also like to convert to cathedral ceilings, but I cannot find any resources which discuss the installation (?) of cathedral ceilings. Two Questions (1) Which of those two projects should go first (or do they need to be coordinated)? (2) the other side of the duplex is a rental unit. Does the entire building need to be converted to cathedral ceilings or can I leave the rental unit as-is?