This is a mystery. About 13 years ago I had our old original bedroom cupboard doors dipped and stripped down to the bare wood. Ever since the edges of both doors have always been almost wet with moisture. The house isn't damp (old as it is) and we run a dehumidifier but the wood always seems to keep moisture. Why ? It isn't the coldest part of the house. I have never understood why wood would do this. The outside wall gets a little damp (furthest from the rads) but that is rectified soon enough with the dehumidifier. I just don't understand why wood not being the coldest materiel would keep moisture. The main doors to the rooms are wood but they don't have any moisture.