XR250 and PhamENG, just to be clear, you both mentioned RO + 3", what are you taking as your RO? I know in door openings they are framed wider than the door itself to accommodate the jamb and shims, so for example, are you saying for a 3068 door you would do 36"+3"+3" = 42" span from center of...
The majority of my career has been in wood design. When I was a young EIT I was told to not worry about using the rough opening as a span and I never really looked back, even though there is often an extra 3". I had an EIT I was training ask the other day if they needed to include the full...