Are you sizing exterior hinged doors the wrong way?

I keep seeing the same mistake across plan sets: architects size exterior doors the same way they size interior doors—by panel width.

But exterior doors cannot be sized like that.
Aluminum door systems especially have multiple layers of frame and stop projection that dramatically reduce the actual clear opening.

Here’s what really happens:

🔹 A “3'-0” door” refers to the panel, not the frame
🔹 Exterior aluminum frames are often 1¾"–2" thick → subtract 3–4 inches
🔹 Door stops add ¾" each side → subtract 1½ inches
🔹 The panel projects into the opening → subtract another inch
🔹 The masonry opening needs 2" beyond the frame for bucking

Add it all up, and that “2'-6" exterior door” an architect calls out may only provide a 24" clear opening—nowhere near ADA minimums and nowhere near what the client thinks they’re getting.

Exterior doors must be sized to the net frame width and height, not the panel.
If you’re not accounting for every frame dimension and every stop, you’re setting up the builder (and owner) for a very unpleasant surprise in the field.

This is why pre-construction detailing matters.
A few minutes reviewing frame profiles can prevent thousands in rework—and ensure the home performs and looks exactly as intended.