An exterior door that swings open on its own indicates:

A door left partly open will stay where it was put if its hinge pins are vertical, because there is no gravitational component along the swing. When the frame is out of plumb the hinge axis tilts, and the door behaves like a weight on an inclined track: it swings toward whichever direction is downhill and does so consistently, every time. That reliability is what makes the symptom diagnostic. It is also easy to confirm on site with a level held against the hinge jamb, which turns a subjective impression into a measurement. The inspector reports the out-of-plumb frame and, because the usual cause is movement in the structure supporting the opening, treats it as a possible indicator of settlement rather than as a door problem to be adjusted away.

A self-swinging door means the hinge axis is tilted, which happens when the frame is out of plumb. Gravity then acts along the swing, and the door drifts consistently in one direction — commonly a consequence of structural movement at the opening.

Door frames are installed plumb so the hinge axis is vertical and the door has no gravitational bias. Foundation settlement, framing shrinkage and header deflection can rack or tilt an opening, and a self-closing or self-opening door is a common early sign.

Doors Do Not Move Themselves. If it drifts, the hinge line is tilted — and something moved the wall to tilt it.

Report it alongside other openings on the same wall. A single drifting door may be an installation error; several on one elevation is a movement pattern.

• •Blaming hinges or lubrication for a directional drift
• •Accepting self-swinging doors as normal
• •Adjusting the door without investigating why the frame tilted