Tons of flood homes on the market here right now, but most of the ones we're looking at have been mucked and remediated prior to being listed for sale (though I'll still spend the $500 to 1K to have them certified mold free prior to beginning rehab), so I'm less interested in "flood rehab" costs and more interested in the average price per SF for a "from the studs" rehab - assuming everything but the roof and exterior needs replacing (plumbing, wiring, HVAC, full interior, etc.) for a mid-grade rehab (granite, but lower end granite, etc.) as these are mid-range houses for the area.

We have a ton of radon here in PA so I submit in my reply if radon comes back high “Seller at sellers expense to install radon remediation system by ABC Radon Specialists and furnish receipts of completed work and satisfactory retesting of the radon level...” this way I know it’s my guy doing it and will be done right.

Any issues found by the inspector, must be remedied or the buyer won't be approved for the loan. 

I know that this can be state specific too, but there will be quite a bit of work being done and that could be a case for remediation which seems very expensive.

If the profit is there, then yes.One thing to consider is proper remediation and being able to prove it. 

I suspect when you look back you will find you did the same.If you got an inspection on the property you may want to reach out to the inspector if anything was obvious but I don't think you will get any help there.You could also try to get an attorney to send a certified letter saying you are considering legal action if you can't come to a resolution but any additional fees may not be worth it.If I were in your shoes I would remedy the safety issues (electrical, plumbing, etc) with licensed contractors making them pull permits, consider this a lesson learned, and move on. 

You might not be able to get insurance until this is remedied.  

It seems like even investors don't want to mess with mold remediation.  

I don't mind doing small projects exposed to it because limited exposure is relatively safe, but as much as you have should have some real remediation.

Let's assume: 6 tenant turns a year$300/turn lease-up fee$700 rehab per turn3 weeks total vacancy per turn$500/unit remedial maintenance per yearIf I include the above factors into the spreadsheet, I get the following:I've talked to a few 4-plex owners and reality is closer to 2% than 9%, unless you bought the property during the crash at a very low price, which is much less than what you would pay today.Questions/Comments On Your Proposed Purchase Ignore "rules".