It is not normal for a basement to always smell damp, and a constant smell may be the sign of an underlying issue such as a lack of ventilation, excess moisture, or even mold. It is a good idea to seek out the cause of the door, checking for leaking pipes, appliances, leaks in walls and ceilings, and issues around any windows you may have. Treating the cause and improving ventilation will help to get rid of the smell for good.