Count on repairs being much higher due to all code upgrades and such that will be required by the appraiser.  

However I'd strongly advise that you be honest with you ability to comprehend financial information and read and interpret tax code.

It related to the tax code treatment of an asset. 

You can try abesentee owners, code violations, unpaid taxes, also look for older owners.

This may open a can of worms but you might consider contacting your local Code Enforcement Office and explain the situation.  

An upcoming public hearing on Monday 6/5/2017 @ City Hall Rm 400 1pm testimonies being heard.item 170519  An Ordinance amending Chapter 19-1300 of the philadelphia code, entitle REAL ESTATE TAXES by creating a tax foreclosure diversion program that requires housing counseling assistance, updating tax installment agreement payments to help taxpayers with financial hardships, and other related items; all under certain terms and conditions.show up and voice your opinions, give your support(I can't imagine who wouldn't support this).

Turns out the side and front porches need to be repaired to code because they are also supports for the roof.

Hopefully building codes will catch up to get buildings above flood areas and more wind resistant. 

This can also be monitored from a smart phone or a laptop in real time panel by panel

If it appraised low due to the condition, you may need to put in double what you are thinking based on code upgrades, electrical updates, etc. 2.