I also discussed this with my contractor yesterday and he claimed aluminium frame cannot be used with heavy wooden door, hence he suggested either wood or metal frame instead. I am considering aluminium frame for my bedroom door which is near the toilet.

I have not talked to my aluminium door vendor about this though.

For my case, it's because the bedroom door is adjacent to the toilet and sometime water from the toilets get splashed out to the floor, in contact with the door frame. Door is few cm off the floor and opened most of the time, so avoided the direct contact with water.

i'm going with metal frame and looking for some water repellent stuff to apply to the bottom of the metal door frame on top of existing paint. any suggestion?

yeah, going ahead with this plan. thanks for sharing!