For some reason I recall that it is Ohio Building code that a bedroom must have a floor finish material other than subfloor. So if you are in a Slab on Grade (SOG) condo, does the code require you to have a floor finish other than the exposed concrete?
A concrete floor is not necessarily a sub-floor, it is may be considered a finished floor material. From Ground floor construction: "A ground-level floor can be an earthen floor made of soil, or be solid ground floors made of concrete slab. Ground level slab floors are uncommon in northern latitudes where freezing provides significant structural problems, except in heated interior spaces such as basements or for outdoor unheated structures such as a gazebo or shed where unitary temperatures are not creating pockets of troublesome meltwaters. Ground-level slab floors are prepared for pouring by grading the site, which usually also involves removing topsoil and other organic materials well away from the slab site. Once the site has reached a suitable firm inorganic base material that is graded further so that it is flat and level, and then topped by spreading a layer-cake of force dispersing sand and gravel. Deeper channels may be dug, especially the slab ends and across the slab width at regular intervals in which a continuous run of rebar is bent and wired to sit at two heights within forming a sub-slab 'concrete girder'. Above the targeted bottom height (coplanar with the compacted sand and gravel topping) a separate grid of rebar or welded wire mesh is usually added to reinforce the concrete, and will be tied to the under slab 'girder' rebar at intervals. The under slab cast girders are used especially if it the slab be used structurally, i.e., to support part of the building."
From the Subfloor construction section: "Floors may be built on beams or joists or use structures like prefabricated hollow core slabs. The subfloor builds on those and attaches by various means particular to the support structure but the support and subfloor together always provides the strength of a floor one can sense underfoot. Nowadays, subfloors are generally made from at least two layers of moisture resistant ('AC' grade, one side finished and sanded flat) plywood or composite sheeting, jointly also termed Underlayments on floor joists of 2x8, 2x10, or 2x12's (dimensional lumber) spaced generally on 16-inch (40.6 cm) centers, in the United States and Canada."
Concrete slabs "may" be used as a sub-floor, but they also are of adequate quality to be considered a finished floor.
To really answer your specific question, you could check out the 1,244 page Ohio Building Code yourself.
I searched through it and see no specific provision saying that concrete is unsatisfactory as a finished floor... The only subfloor requirements I saw had to do with fire resistance, load bearing capabilities, and they all appeared to be related to wooden subfloors from my brief look over.
I'm pretty sure (Nothing is ever certain in the face of government meddling) that this is fine, per Ohio state code (your city or county may differ), and I verified this with a search through codes.ohio.gov.
Concrete floors are common and can be a fine choice depending upon your circumstances.
- Section 5101:2-9-05 requires padding over hard floor surfaces in rooms used for residential daycare.
- Concrete flooring that is unsealed, or that doesn't have a suitable vapor barrier underneath it, may be in violation of water-permeability and/or radon regulations.
- Your city or county may differ. Consult your local permitting agency.