From what to what do you measure when knowing what size pre-hung exterior door will fit?
For what I think should be the standard 36"x80", the contractor through the orange store came back with entry unit size to order = 37.5" x 81.5".
So with the guy at the store saying i gotta go by what they say will fit there's no door size that is specifically 37-1/2 x 81-1/2.
the exterior of the house is sided, it's a one level ranch. looking from the outside the door is a left hand in swing. On the exterior to the left of door the wall juts out 90° so the rough opening can't really be opened up on that side or shouldn't. But on the right side there's plenty of room to work with, as well as about a foot above the door to roof soffit which is flashing not siding.