@James Freeman Since you need a 4 bedroom, I would recommend that you look into the possibility of building an ADU, Accessory Dwelling Unit, to help supplement your current income.

You can insulate floors, bathroom & bed room walls for noise but its not required.IRC - International building code for one and two family dwellings.

The premium for the policy goes based on the dwelling coverage of the structure.

Private flood generally requires you to match the Home Owners Coverage A  dwelling amount with the flood amount. 

Hey all we just closed on a property in Denton and I am looking into getting the process started on building out an additional dwelling unit.

I’ll be sure to ask other investors about how the process works with the historic board, luckily I know another investor in town who has dealt with them.Our plan may eventually be to cut up this building into multiple residential dwellings if the city allows.

I don't have experience with it, but I would imagine those policies would be a lot higher higher than a traditional dwelling policy. 

It may be a bit more difficult to find a lender that will issue a HELOC on a non-owner occupied dwelling, but I'm sure you can find one.

I had a dream, which was not all a dream.The bright sun was extinguished, and the starsDid wander darkling in the eternal space,Rayless, and pathless, and the icy earthSwung blind and blackening in the moonless air;Morn came and went—and came, and brought no day,And men forgot their passions in the dreadOf this their desolation; and all heartsWere chilled into a selfish prayer for light:And they did live by watchfires—and the thrones,The palaces of crowned kings—the huts,The habitations of all things which dwell,Were burnt for beacons; cities were consumed,And men were gathered round their blazing homesTo look once more into each other's face...

The main difference between the homeowners policy (HO3) and dwelling policy (DP) is the occupancy.