How would you do "Due Diligence" when you know the house isn't up to code?

[Todd Runstein]

http://www.zillow.com/homedetails/1407-SE-175th-Pl...

It says "House is being sold in as-is condition and needs extensive work. NOT financiable. House was updated by the prior owner who did not have the work permitted. City will require new purchaser to bring the house up to code. Buyer to do due diligence."

So, how would one find out what really needs to be done? It seems like looking at the condition isn't going to tell you the full scope of the work required. So, while I assume you'd call the "City", but who would you ask for? How would you do due diligence to determine whether this was a property you were interested in flipping?