They are estimating 20k plus in upgrades such as hurricane impact windows and doors, brand new energy efficient AC units and duct work (to ensure soundproofing) and insulation.

As I stated earlier the duct work was already done.

I'm still in the beginning stages and haven't gotten exact quotes yet, but have a ballpark idea of what we're looking at.Option 1:Separating the existing ductwork to 2 zones, and adding a second furnace...

The pipes froze and busted everywhere and the basement was destroyed, along with all of the HVAC ductwork and a decent amount of flooded water upstairs.

You will see how fast the tenant will forget all about the ductwork, once you tell them there will be an increase in the rent.

The duct work may be able to be cleaned, but I see replacement of that as well.  

We added a bathroom to the second story, new roof, new wiring, new duct work, all new plumbing, re-framed the second story, etc.I have before and after photos of the flip and can link to the sold listing if anyone is interested in looking (not sure if that's OK or not). 

But if units are new they can be designed to handle duct work.

I was quoted $29k for 2, 2 room mini splits systems to put ac into my duplex that has no ductwork.

There is one property right now that I want to put an offer down for that has a renovated basement with 6 ft ceilings however there are sections that are under the required height limit for some duct work.