While new development due diligence might easily take 6 months +  so you would likely loose the contract before they would be able to complete their DD on the purchase.

Current Situation: I purchased my first duplex back in June and have lived in it the last several months while I am giving the place a complete update (new flooring, paint, windows.. etc.).

The flooring completely torn out, the place was wired specifically to grow the green stuff, and they had put in all sorts of piping and ventilation systems.

I just got the good down payment, and had a real estate attorney draw up the contract.If they don't complete the transaction, then they lose some money. 

Without the appraisal being completed, I am guessing that is a condition and one I personally wouldn't write off on.

If there isn’t significant equity value, I wouldn’t bother, as getting an ADU completed in this city as a royal PITA.An ADU can’t convert to condo btw. 

He wants to flip after work completed. 3 to 6 month estimated rehab. 

You must be able to know what works for the investor and also works for you . so make sure you are factoring enough cushion for negotiations .3# Estimates Be able to access the approximate renovation cost for your investors . complete a spreadsheet that will help you calculate cost .

Having to completely redo the roof on a friend's addition that's only ten years old because they did this.

Also have some verbiage to ensure subs are paid after work is completed.