Very large farmhouse built in 1900. Multi-Family BRRR now in progress

I bought a 3,068 sq ft farmhouse originally built in 1900 for super cheap.  First, as a seller financed deal because the tenants were horrible and the rents were low.  But, that's why the seller wanted out badly, and was willing to sell for cheap and with 100% financing.

I got the tenants out on a 20-Day Notice to Vacate, and then did a simple re-carpet and paint in order to rent it out to better tenants and at a higher rent.  

Then, I did a cash-out refinance with a bank.  The new appraisal was based on the higher rent, so I was able to pull out all the money I had put in to the place and have 25% equity remaining in it.  

A year later, I am now taking the unused very large attic and creating a new 4 bedroom, 2 bath unit upstairs.  I'm using a HELOC to finance the construction and permits, and then plan on refinancing again at the new appraised value once I have new tenants in.