Replace all doors in the house ?

[Marita Jojo]

I am renovating an old house for rental and one question keeps coming back is whether to replace the old solid wooden doors with the new cardboard doors ? The door knobs of a few needs replacement and as they are not the standard thickness can’t use the new privacy knobs. Does it affect appraisals if the old doors are painted and used ? I think old doors can last much longer. What do you do for your properties?