And are the DIY folks including the costs of their labor or are they only counting cost of materials?

I think mine cost 1800 for a 400,000 LOC, but I'm a noob and may have got a bad deal.

I own two properties there, but insurance costs have skyrocketed.Lately, securing home insurance has become increasingly challenging due to the high risk of hurricanes, flooding, and other factors.

It doesn’t matter if you sell it for more or less than your purchase price as you’ve adjusted your cost basis with the depreciation.

@Sean Graham isn’t your example paying for another cost segregation, which will cost more than a 1031, just to break even on taxes?

Also you need differentiate your construction costs (hard cost) vs the development costs (soft costs). 

Quote from @Lee Ripma: @Sean Pedeflous - I have not personally used this company but they have an algorithm based rapid cost seg which is similar to the two others I have used, KBKG and DIYcostseg.com.

How do you secure funds quickly?

Whether or not you would benefit from a cost segregation study depends on multiple factors. 

And you have to expect holding costs.