Clearly, they failed in their primary responsibility to you as their layer of due diligence was a mere gossamer like patina.

The primary issue is that building small unit in a single count is some of the most expensive development.In addition, in most jurisdictions the primary unit will become rent controlled (assuming more than 15 years old).  

It would be his primary residence so most likely a duplex or triplex house hack. 

I have a rental down the street that was my primary for a few years, so I am not just someone looking for a quick deal.

However, are you planning to do a 1031 exchange, or is this a primary residence? 

While this doesn’t apply to investment properties, it’s useful for primary residence or house-hacking strategies.3.60-Day Rollover Rule: You can withdraw funds from your IRA and avoid penalties as long as you return the money within 60 days.

The two existing LTR units (on my family’s property) were built 5–8 years ago at a cost of about $80,000 per unit, so I’m estimating a 20% increase in costs for the new builds.My plan is to use the equity in the land as the down payment for the construction loan, which I expect will make closing costs the primary upfront expense.

-Primary Residence. 

Or buy a 5bed/3bath house, live in the primary suite and rent the other spaces out.

So, if interest rates are a buyer’s primary roadblock, then I recommend negotiating a rate buydown at a seller’s expense or looking at new construction, where builders are offering rate reductions and other substantial incentives.What if I’m a seller?