Q: I see there are many options on the doors, i.e. walnut, birch, oak etc. and noted there is an option for "Hardboard" is this an exterior grade, or does it have moisture resistance properties?
None of the wood doors that you would find in our website would be specifically intended for an exterior application and in fact I would dissuade you from considering any of these doors for your application because they would not carry or an exterior door warranty.
Having said that, there are indeed countless instances when clients have purchased the same door and have successfully used it exterior applications with no trouble whatsoever and in fact we can do things to help reduce the potential for failure in an exterior environment such as using high quality structural lumber and type 2 exterior rated glue that I suppose you could put on several coats of a marine quality clear to the material but again technically these doors exterior warranty.
If you had no choice but to use a door where there would be no warranty for an exterior application I would coat all six sides of the door as thoroughly as possible not less than three complete times and would predict that your success would be practically complete.
Q: Would you happen to know what the density is for a 1 3/4" thick solid core walnut door is?
Depends on the particle board that's used - there's two different densities used in the door business.
LD1 = 28.1 - 30.6 lb as seen here:
LD2 = 31.2-34.3 lb as seen here:
I have personally used both cores in flush architectural wood door construction and I can tell you that the denser LD2 is substantially heavier in weight and is considered unnecessary in my experience to use over the very typical LD1.
I'm also assuming that you're referring to a solid core particle board and not stave lumber core or structural composite lumber etc
Q: By any chance do you build off (not standard) size doors. I am in need of 2 solid cord wood doors 2' x 4', and regarding the inside of the door would that be particle board or solid lumber and also that all four sides are finished wood.
A: We do build custom doors in the core would not be solid wood though it could be what we call lumber core (think of butcher block) or would be solid structural lumber (which is known in the industry is Timberstrand or ‘LSL’) or finally it could be particle board as well. The vertical sides would be matching/compatible to the veneer the rails can be as well when specified that way, in fact we can specify every detail of the door physically so as to meet your requirements.