For example, most Developers in the Seattle area are taking many properties and turning them to condos since that is a booming market with high rental rates And sometimes more conveniently built and accommodating then a SFH.

The license doesn't cost more, the service and quality does.And a note on that cost, in my experience hiring contractors, only a small percentage of the cost savings was due to finding the right guy who is willing to work for less.

I highly recommend requiring ID, selfie, and pics of CC front and back.  

I would highly recommend talking to Jeff Weller at Coast 2 Coast and Fernando Corona both are also PadSplit hosts but we're some of the first expert lenders .

BIG high-5! 

If you want to quote out high efficiency boilers for six Tripple deckers for example requiring installation of separate gas, meters etc. etc. - that might be a situation where you would want to work with a contractor directly because you would have lots of different options with widely varying costs.

I looked into this at more than one occasion, because Milwaukee has such an old housing stock, everything is 60-120 years old.Most of the new apartments we see are 4 and 5 star developments with very high rents, this allows to offset the high cost of construction a little better.

Couple other things to consider, property / school taxes are high, and tenants have lots of rights.

Even if you can find insurance now, premiums will likely remain high, and resale value could be impacted unless the wiring is updated.

I won't just write them all here but I highly recommend contacting a qualified 1031 intermediary to walk you through the process.