Adjust Your Projection to Account for the Pitch
When choosing a size for your awning, note that the awnings' projections are measured from top to front; they do not allow for the pitch of the awning.
Example: Say you have a deck that extends 10 ft away from your home.
Per the pitch description above, you will need 3 inches above the door for every 12 inches of the awning's projection, which in this case would be 30 inches.
However, if you were to select an Economy Stationary Patio Awning with a 10-foot projection, the awning would extend only 9 ft 9 in from the house, because of the angle of the awning.