Looking at buying property with barn on it that was not permitted

[Kelly Beasley]

Hi all,

I have a property under contract in Tucson, Az. It's just under 5 acres with a 1080 SF house and a 4000+sf center-aisle barn on it. The house and barn are full of deferred maintenance. I can't find a permit on the barn structure. Seems the city didn't know about it until 2016 when it mentions the structure and the taxes jumped heavily. But it was built around 1992. Not understanding this, but whatever. 

My biggest concern now is that I can't find a permit for that barn and my agent doesn't think it was permitted.

How concerned should I be? If I were to use this for negotiation, how much negotiation are we talking here? I am already going to ask for a TON of repairs to be made, which they are not going to do. So I am going to ask for HUGE credit, as BOTH structures need new roofs as does the carport ($17K), the interior of the house pretty much needs a gut, and to bring the property up to rental standard with horses will cost me about $39,000. 

It's under contract for $146, which is $7K over asking price. (It LOOKED great on paper until I got there and saw it with my own eyes)

Now I was going to go down by the numbers above, so I was going to drop to about $105K. (We shall see if they even go for that)

But now I am concerned because I need to add doors to the stalls to add paddocks, or the barn is worthless to me. 

This may require a permit, which would probably alert the city that it WASN'T permitted before, prompting... what? An inspection? If wiring is all wrong, etc, does that mean I will be forced to change whatever is wrong?

Advice here? Anybody had nightmare with an unpermitted addition or whatnot? Or no big deal?

How much negotiation room do I have with this? Thoughts? Thanks!