Drywall Cracks Above Doors and Windows: What They Mean

If foundation movement had a handwriting, it would be the diagonal crack running up from a door frame's corner. It's the most common interior symptom we're shown — and one of the most over- and under-reacted to, often in the same house. The good news: this crack is unusually readable once you know what it's reporting.

Why the corners, always the corners

A wall with a hole in it is strong everywhere except around the hole. When the foundation under that wall deflects even slightly, the wall must absorb a small change in shape — and all of that strain funnels to the weakest points: the top corners of doors and windows. The drywall tears there first, diagonally, following the strain direction. The crack isn't damage so much as instrumentation — a strain gauge the house installed for free.

Reading the gauge

• Direction: the crack generally climbs away from the side of the house that's dropping. Cracks at several openings all leaning the same way are pointing at the same low corner.
• Symmetry: one corner of the opening cracked wide while the other is hairline (like the diagram) means racking — real differential. Matching hairlines both sides is usually gentle whole-wall flexing.
• Texture of the tear: a crack through paint only (it flakes at the edges) is old and re-opening seasonally; a fresh tear through paper is recent movement. Both matter, but they date the story differently.
• The cluster rule: the crack alone is a question. Pair it with a sticking door or exterior stair-step in the same zone and the question is answering itself.

When it earns the survey

Widening past about 1/8″, fresh paper tears at multiple openings in one zone, or any crack with corroborating friends — that's elevation-survey territory. Not because catastrophe is near (it almost never is), but because the gauge is now reading something worth measuring properly. Half the time the survey's answer is “old movement, finished, patch away” — and that answer is worth having in writing.