I need a new front door on my house. I've been looking around and I’ve noticed a big price difference in external hardwood doors and internal hardwood doors. I’d like to know if its possible to use an internal hardwood door as an external one. The only difference is the thickness of the door so how would this prevent me from using it as a front door? If there are any other reason I can't use an internal hardwood door as a front door could you please let me know.