The Short Answer
Both explanations are common, and telling them apart is straightforward once you know what to look at.
Sticking that comes and goes with the weather is almost always timber responding to humidity. Sticking that worsens steadily, or that leaves a visibly uneven gap around the door, points toward the opening itself having moved out of square. That second case is when a foundation evaluation becomes the useful next step.
The Seasonal Explanation
Timber is hygroscopic. It absorbs moisture from humid air and releases it in dry air, and its dimensions change as it does. In San Antonio the annual swing is substantial: a humid spring followed by a hot, dry summer produces a genuine measurable difference in door and frame dimensions.
The signature of seasonal sticking:
- It appears at a particular time of year and resolves at another.
- The gap around the door stays roughly parallel, it is simply too small.
- Multiple doors across the house behave similarly at the same time.
- Exterior doors and doors near bathrooms or laundries are affected more.
Nothing about this requires a foundation contractor. It is what timber does.
The Structural Explanation
When a foundation moves unevenly, the framing above it distorts. A door opening that was built square becomes slightly out of square, a condition usually described as racking. The door itself is still rectangular, so it now binds against a frame that is no longer parallel to it.
The signature of structural racking:
- The gap around the door is visibly uneven: wider at the top on one side, closing at the opposite corner.
- The door binds at one specific corner rather than along a whole edge.
- The condition has worsened progressively over years rather than cycling with the seasons.
- Cracking has appeared at the corner of the same opening or nearby.
- The floor in that area feels or measures uneven.
A Simple Test You Can Do Today
Open the door about halfway and look at the gap between the door edge and the frame all the way round.
If the gap is parallel along its whole length, top and sides, the opening is still square and the door is simply oversized for it right now. That is consistent with timber movement.
If the gap tapers, wide at one corner and closing at the diagonally opposite one, the opening has racked. That is consistent with structural movement and it is worth documenting properly.
Repeat the observation on several doors. If one door in the house shows a tapering gap and the rest are fine, note where that door is. If several doors on the same side of the house show it, that is a pattern with a shape, which is exactly what an elevation survey is designed to measure.
Why not just plane the door?
Because it works, which is the problem. Planing removes the binding and it also removes your reference point. If the opening is still moving, the door binds again in eighteen months and you have lost the ability to compare. Document first, adjust second.
What to Document
- Which doors and windows stick, listed room by room.
- Where each one catches: top corner, latch side, bottom edge.
- Whether the gap is parallel or tapering.
- Whether the condition is new, seasonal, or steadily worsening.
- Photographs of the gap at the point it closes, with the date.
- Any cracking at the corners of the same opening.
Note the season when you record this, and repeat it at the opposite end of the year. The comparison is the useful part.
Other Causes Worth Ruling Out
Not everything is humidity or foundations. Hinges work loose and let a door drop. Strike plates shift. Carpet or new flooring reduces bottom clearance. Paint builds up on a frequently painted frame. Exterior doors move with weatherstripping compression.
Check the obvious mechanical causes before assuming either of the bigger explanations. A door that binds only at the latch and has a visibly loose top hinge is telling you about a screw, not about your slab.
When to Request an Evaluation
Request one when the gap is tapering rather than parallel, when the problem has worsened steadily over years, when several doors on the same side of the house are affected, or when sticking appears alongside cracking and uneven or sloping floors in the same area.
A single seasonal sticking door with a parallel gap does not need a foundation contractor. We would rather tell you that than book a visit.