Why Do My Doors Stick in Summer but Not in Winter?

Quick Answer

Wood doors absorb moisture from humid summer air and expand, making them tight in the frame. In winter, drier air causes the wood to contract and the sticking stops. The fix depends on severity: sanding the tight edge works for mild cases, but sealing all six sides of the door with paint or finish is the best long-term prevention.

The Physics of a Sticky Door

Wood is hygroscopic — it absorbs and releases moisture from the surrounding air. When relative humidity rises in summer, wood fibers soak up water vapor and swell. When humidity drops in winter, they release that moisture and shrink.

This isn't a small effect. A solid wood door can expand by as much as 1/8 inch across its width during a humid summer. The frame it sits in, typically made from the same type of wood, also expands — but not always by the same amount, especially if one side of the frame is exposed to different conditions than the other.

The result is a door that rubs, sticks, or refuses to latch during the humid months, then works perfectly fine once the air dries out. It's one of the most common seasonal annoyances in homes, and it's nothing to worry about structurally. But it is annoying.

Why Some Doors Stick and Others Don't

Not every door in your house will behave the same way. Several factors determine which doors are most affected:

Exterior doors are exposed to outdoor humidity on one side and indoor conditions on the other. This differential can cause uneven expansion, making the door warp slightly in addition to swelling.

Bathroom and kitchen doors are near moisture sources. A bathroom without proper ventilation can significantly increase the humidity around a nearby door.

Unpainted or unsealed edges. If the top, bottom, or hinge edge of a door was never painted or sealed, moisture can enter the wood much more easily through those raw surfaces. This is surprisingly common — the edges you don't see are often the ones the painter skipped.

Solid wood doors expand more than hollow-core doors. The more wood, the more expansion.

If you've noticed that your hardwood floors squeak only in winter, you're seeing the flip side of the same phenomenon — wood shrinking in dry conditions creates gaps that allow movement and noise.

Fixes, From Simple to Thorough

Wait and see (for new homes). If your home is less than two years old, the framing lumber is still drying out and settling. Doors that stick during the first summer may not stick after the house has gone through a couple of seasonal cycles. Don't plane a door in July that you haven't observed through a full year.

Identify the contact point. Close the door slowly and observe where it first makes contact with the frame. You can also slide a piece of paper around the edges to find where it grabs. Mark the tight spot with a pencil.

Sand or plane the tight edge. For mild sticking (the door closes but requires a push), 60-grit sandpaper on a sanding block is usually enough. For more severe cases, remove the door and use a hand plane to take off a thin shaving along the tight edge. Remove material gradually — you can always take off more, but you can't put it back.

Seal all six sides. This is the real long-term solution. A door has six surfaces: front, back, top, bottom, hinge edge, and latch edge. If all six are sealed with paint, polyurethane, or another finish, moisture exchange slows dramatically, and expansion is minimized. Take the door off its hinges, seal the top and bottom edges that are usually left raw, and rehang it.

Check the hinges. Sometimes a door sticks not because of expansion but because a hinge screw has loosened, allowing the door to sag. Tighten all hinge screws. If a screw spins freely, the hole has stripped — push a wooden toothpick dipped in wood glue into the hole, let it dry, and re-drive the screw.

Consider a dehumidifier. If your indoor humidity regularly climbs above 60% in summer, a dehumidifier can reduce moisture throughout the house. This helps with sticking doors, but it also protects hardwood floors, prevents musty smells, and reduces the conditions that encourage mold. Keeping indoor humidity between 40% and 55% is the sweet spot for both comfort and wood stability.

The relationship between wood and moisture shows up all over a home. Understanding it helps explain everything from squeaky floors to why proper ventilation matters in spaces like attics and crawl spaces.