We just received the warranty deed yesterday from the county.

Some damage from WDI, which seller will have to address this before close.Seller is paying all closing costs, survey & title, they did a rate buy down to 5.49%, and a year warranty. 

While concerns about vacancies are valid, a great deal will often outweigh the short-term impact of a couple of months without rent, especially considering that it usually takes time to close on a property.

It will have to be a pass through/disregarded LLC to keep the tax payer the same and the 1031 valid.

You can only play games for so long.Chances are your next door neighbor is an IRS agent and turns you in when your tenants blocks their drive or some other random event disturbing your IRS neighbor.ADU catches fire and your insurance won't cover you, because it was an illegal and unpermitted structure.The city inspector told the last guy not to build or rent it, and is now pissed and wants to make an example of you and just red tags the whole property and no one can occupy for the next 1-2-3 years while you wait for a hearing.Then when you get the hearing, "staff" recommends you tear the whole structure down, and if you still want an ADU, you can apply for a permit and rebuild it.Your tenant quits paying rent and won't move out and you can't evict them, because there is no valid lease and they're just your "roommate".Probably a dozen other bad things can happen to you when you do stuff like this. 

All valid points and why I'm hesitant Kai.

You can get a home inspector but like James stated many builders offer/include a warranty.

All caps is kind of loud but you make valid points. 

Its a local business, not a national service which gives me more comfort as I'm not a fan of "home warranty."

They’re often familiar with market-specific expenses and can help validate your estimates.Lastly, as you analyze more deals, keep track of actual expenses on your properties or properties you’ve researched.