Seems renovating this part of the attic would require ceiling insulation, drywall, flooring, electrical outlets, & heating source.My concern is that a reappraisal wouldn't add anything to legal square footage. 

Martin I agree and fully expect to fire rate the floor/ceiling separating the units but the exterior walls that the units don't share does not seem typical and that's what I'm looking for clarification on.  

White walls white ceilings is great.

So this is an older home - 2 story with low ceilings and no attic so no room for ductwork. 

Huge vaunted great room ceiling. 

I am building a home that has toungue and groove interior walls and ceilings. 

We are doing some new vinyl plank flooring (not through the entire house), paint on the main floor, minor electrical work, replacing a door, new ceiling fan, minor plumbing, etc.. 

Then I bumped rents up $50 between each tenant until I felt like I hit the ceiling. 

Power stripped 60 years of paint from the floor-to-ceiling river rock fire place.

new plumbing, electrical, ceiling, walls, porch, patio etc.