Door and window hardware may occasionally cause sticking. If a door is sticking near the top of its frame, its hinges may be the culprit, while sticking near the middle can indicate a loose strike plate—both relatively minor issues. However, excess contact elsewhere on the frame is likely due to humidity or foundation settling.
While humidity can cause wood to swell, leading to temporary sticking, true foundation issues present more persistent symptoms that worsen over time. If your doors and windows stick consistently, even when humidity levels are low, it’s likely that you have a foundation problem. A professional inspection can accurately diagnose the cause.