I think I remember a thread or two regarding the subject and am working on an older house that has a parapet roof with the roof rafters running parallel to the baseline (versus the default perpendicular) and haven't found a method to reproduce the condition. I'm aware that Chief does not like to frame this way and can probably take care of any details/sections pretty easily but am curious about methods or workarounds.   Oh yeah the roof is not flat but only 1/4" ft slope.   T