Years ago I requested a quote for some solid doors and was floored by the
cost. In response to my question, the answer was that in some parts of the
world, a south facing door protected by a storm door can reach an incredibly
high temp with exterior moisture content, meanwhile the interior surface can
be basking in air-conditioned comfort with lower humidity. That obviously is
a recipe for warping and god lnows what else, so basically he explained
warranty claims drove the cost up so high. 

 

Up here in GWN, the inverse can occur..outside temp -30C, zero humidty,
while inside is comfoprtable 70F, with a humidifier running, or (as I;ve
experienced, the clothes dryer veented inside which raised humidt to 80%

 

That being said, most doors come with some kind of document that says  All
surfaces have to be finished or there's no warranty. Of all the painters
I've encountered over the years a a finishing/cabinet guy, the vast majority
are unaware of this requirement, or just blithely ignore it.

 

Trust your mentor pointed this requirement out.

 

Regards

Eric