Creating Habitable Cellar?

I have an accepted offer on a loft space, ground floor in a 15 unit renovated building. There is a cellar beneath the unit. The ceiling heights on the first floor are 12 ft. and around 6 ft. in the cellar. I am wondering (prematurely, I am sure a contractor during inspection can tell me) if I can raise the floor/cellar ceiling and use the cellar as habitable space. Not to rent out, just to have 2nd bedroom, bathroom and office. I was also thinking of knocking out part of the floor altogether to bring light down there from above. Anyway my question is will this be counted as sellable square footage if I ever resell? (ceiling will be around 8+feet in cellar, but no direct window light or exit).

By ran |