I purchased a prehung door and in the process of checking the rough opening of our old house I found that the exterior wall slants back and is therefore not plumb. If I install the door so that it is plumb the bottom of the door's brickmold is flush but the top is about an inch away from the house. If I install the door so that it is flush with the outside of the house it does not seem to open and close properly (although I did not spend much time trying to work with it). I've seen all kinds of instructions on dealing with problems but all of the DIY instructions assume your exterior wall is plumb.
What is the proper way to deal with this? Do I install the door flush or plumb?
Take a picture of the threshold (bottom) also so we can see if you could cut 1/2" off the shake mold to move the whole bottom inside that much and still be weather-tight. 1. Measure your wall thickness at top and bottom, each side jamb. 2. Check level on the threshold also, from jamb to jamb. 3. Are the width and height door size plus 2-1/2"?
Be safe, Gary
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.