Hey there! For a conventional loan appraisal the property doesn't have to be in perfect condition but if there is a lot of damage you will most likely be looking at a rehab loan. For a conventional appraisal to work, you will need to have the electricity and water turned on, generally the walls need to be complete to be counted as a living area, working heat source, plumbing, and the roof needs to be in fair condition and the structure itself be sound.
Appraisals on conventional loans, have gotten stricter than they were a few years ago. It is not uncommon for an appraisal to be reviewed on a REO purchase and interior photos requested to determine the condition if there is any doubt.
If you want to look into rehab loans, I work for a bank that will still do 100% investor rehab financing, depending on the specifics of the situation. Feel free to email me.