I would get permits unless you plan on ripping out his work when he moves out.

, when an attorney doesn't publish your FC in the newspaper so it has to be delayed 2 months, when the attorney hands the keys to a cash for keys deal before you had it inspected and the homeowner stole the AC unit/water heater and ripped out the HVAC (all true stories from the past year).. 

The walls have been completely ripped out to re-do the job.

After getting ripped off from the listing agents preferred contractor I mentioned above, I found a great agent I could trust and we built a great business relationship.

Kilz prime all walls and do ozone treatment before you start to replace any of the stuff you've ripped out..

Hey everyone,
Trying to get some feedback on what I should do with a large slab of concrete in the back yard of a rental property I just purchased. The slab (to my memory) is about 25' x 15' by 6" and very, very ugly....

I guess Banks are a rip off haha.

If it's zoned as a SFH and only has one APN lookup your local laws on 'Accessory Dwelling Units' it's entirely possible the conversion was unpermitted and you'll get in trouble/have to rip out the 2nd unit if any code inspector finds out about it. 

I am a re broker and NMLS licensed mortgage banker.. as well as an attorney is qualified... go to the real estate commission website and look up there.. it was senate bill  1036  or something close to that its been a few years and my memory is not what it used to be  LOL.of course there are those who could give a rip but I can tell you .. you get turned into the AG and your in a world of hurt....

I guarantee you that many ripped and torn off shingles will be found in his snow pile and he will have roof issues as well.