If a door won't close properly due to swollen wood in the door frame, you can try the following steps to fix the issue:
Identify the swollen areas: Inspect the door frame to locate the areas where the wood is swollen, causing the door to stick or not close properly.
Remove the door: To work on the door frame effectively, you should remove the door from its hinges. This can usually be done by removing the hinge pins with a hammer and a flathead screwdriver. Have someone help you with this step as doors can be heavy and awkward to handle.
Sand down the swollen wood: Use sandpaper or a power sander to carefully sand down the swollen areas on the door frame. The goal is to remove enough material to create enough space for the door to close smoothly. Take your time and check the fit of the door frequently as you sand to avoid overdoing it.
Check for other issues: While the door is removed, check for any other potential issues that could be affecting its proper functioning. Look for loose screws, hinges that need adjustment, or any other damage that might have contributed to the problem.
Seal or paint the door frame: After sanding, it's essential to protect the door frame from future moisture damage. Apply a suitable sealant or paint to the sanded areas to prevent further swelling and to preserve the wood.
Rehang the door: Once you've sanded and finished the door frame, carefully rehang the door back on its hinges. Make sure the hinges are properly aligned and secure, and check that the door now closes smoothly and without sticking.
Adjust the strike plate (optional): If the door still doesn't close properly, you might need to adjust the strike plate on the door jamb. Loosen the screws holding the strike plate in place, slightly shift the plate in the direction needed for a better fit, and then tighten the screws back in place.
If you are unsure about the process or the extent of the damage, it's best to consult a professional carpenter or handyman for assistance. They can ensure the door is properly repaired and working correctly, especially if there are significant structural issues with the door frame.