I’ve replaced dozens of rotten entry doors in my time as a carpenter. Unfortunately, most of those rotten doors never had a chance in the first place. In my opinion, the single largest cause of failing doors is improper installation and flashing. In this case the door looks weathered and it is. It is not operating properly and it is very draft. But you never know what you are really dealing with until you get the old door out and get a good look at the rough opening. The first thing I’m going to door here is take the door off the hinges.
I take the door off the hinges and then begin to pry off the interior and exterior casing with a small flat bar.
I am going to be making new exterior casing for the door, but I hope to re-use the traditional pediment above the door, so I am particularly careful not to damage it as I take it down.
To do a proper job flashing the sill, I have to remove the riser below the door as well.
With a reciprocating saw and a demolition blade I cut the fasteners holding the door jamb to the framing and then cut the jamb into pieces. Using the lower pieces of the jamb as a lever, I peel the threshold from the sill.
Before removing the siding, I number each shingle that I plan to reuse. I remove the siding from the top down, the opposite of how it is installed.
With the rough opening exposed, I can get a good look at the condition of the framing and inspect for rot. If I find any damage, I’ll have to repair the framing before I move on to the first steps of flashing which happen before the door is installed.