NC Commercial RE sale - tax question - how much will I owe?

[Mike Enzwiler]

I am looking to sell my commercial warehouse here in NC.  I have owned it for 19 years but have refinanced it a couple of times over that period.  So, being that the amount of depreciation I take or have taken effects my tax bill, how do I calculate this?   Does the depreciation schedule start over when I refinanced or does it just continue since my original purchase?  What other factors do I need to consider?  

Thanks for your help,    Mike 

FYI- The building is 10,000sq ft portion of a 15,000sq ft building.  My portion (10K sq ft) is broken up into 3 flex space units (5000, 2500 and 2500).  All units have long term leases and generate $7300/mo   Taxes are $8800/year.   Expenses are insurance,water and landscape ($4K/yr).  New warehouses in the park are getting $120sq ft.  I want $90sq ft.  I have don't have a realtor nor am I looking to use one for this.  Also, it's not listed anywhere.