Separating a duplex attic to become an independent apartment

[Walker Furpahs]

So, I got a duplex a few years ago and finally got around looking at the Columbus zoning map, it turns out that the building is already zoned for three units, not two, I want to turn the attic into the third unit, I’m thinking to add a proper staircase fire escape and run independent utilities up to the unit through one side that’s currently under construction. I don’t know anything about this process and am hoping someone has some insight. I know that if I put a door between the units, I’ll meet the square footage requirements for headroom, but other than that, I’m not sure how to proceed.

[Simon Ashbaugh]

I would start by finding an engineer who can tell you if your floor system and lower level framing can support a 3rd apartment. then figuring out egress and best way to run utilities up there. another thing to think about is if you can support parking for 3 units i.e. street, back of lot, etc.