Chicago basement ceiling height: 7'6" or 7'?

Question

I have a non conforming basement unit in a legal 3 flat. The ceilings in the basement are a hair over 7' (full size door fits), and trying to understand whether to duplex down my first floor unit and go from 3/1 to 4/2 bed/bath legally.

Per the link below, I'm seeing that in a "sleeping space" that the ceilings are permitted to be 7' (or less, for a bathroom):

https://www.map-strategies.com...

However, the chicago code says the height should be 7' 6":https://chicagocode.org/13-64-....

So which is it?

Jonathan Klemm · Answer

@Samuel Pavlovcik - Golden nuggets for all of us chicago real estate investors.  Knowing codes is so valuable or better yet......having an architect on your team who knows them better then the inspectors!

Samuel Pavlovcik · Answer

@Jonathan Klemm, I did have one client who got hit with a Vacate Notice on the existing finished basement of their 1st floor Duplex-Down unit because it was less than 7'. That being said, it wactually ranged between 6'-5" - 6'-10". In the end; they would have had to dig-down the basement in order to achieve the necessary height, and then ended up just deciding to vacate the basement and convert it to "Heat and Storage" and ended up loosing all of their rentable potential from the basement level...

Most of our clients see it as too much of a risk to try to keep the existing basement floor when it is around 6'-11" - 7'-1" rough. Typically these old basement slabs are something like a 3/4" thick slush coat of oncrete over dirt, and are sloping slightly towards floor drains which means the floors are not level, and the ceiling height can range a bit. All it takes is one inspector to be perticular about the measurement, and it could cost you your entire basement, or add the cost of trying to lower the slab After you completed your remodel, which means a lot of rework...

One additional bit of information related to the City of Chicago Building code which I hope will help someone in a tight situation down the road. In basements of R-5 Occupancy Buildings (buildings containing 1 to 3 residential units and no other occupancy/use) are Not required to have drywall at the ceiling!:

In accordance with the City of Chicago Building Code Title 14B:14B-6-601Table 601Type V-A construction:Floor Construction and Associated Structural members:The table notes a 1 hour fire resistance rating; however, in accordance with exception (g):"In single family dwellings, the floor construction over basements and unexcavated spacesbelow the first story above grade plane is not required to have a fire-resistance rating."

Additionally, 14B-2-202 Defines a Basement as:“Basement: A story that is not a story above grade plane.”

Additionally, 14B-6-605 notes:“Except in buildings of group R-5 occupancy, floor construction over basements shall have afire-resistance rating of not less than 1 hour.”

This means that if you are Very close to missing the 7'-0" mark, you can leave the ceiling unfinished and measure from the floor finish (a thin LVT or Vinyl tile would be recommended) and the Underside of the Joist.

Note: Rooms containing gas-fired appliances (i.e. Utility/Laundry rooms) shall have 1 layer of 5/8” Type-X drywall on both sides of the surrounding walls, and 1 layer of 5/8” Type-X drywall at the ceiling. This won't be an issue for the ceiling height, as these areas are allowed to be less than 7'-0" as previously noted in this thread.

Samuel Pavlovcik · Answer

@Jonathan Klemm thanks for the mention.

@Abby S. The codes can definitely be a bit confusing. 1st and foremost it's important to ensure you are using the correct code! I noticed your link was actually to the previous Chicago Building Code "13B". The City of Chicago updated their code in 2019 to "14B". I have proivided the link below for your convenience:

https://codes.iccsafe.org/cont...

In accordance with 14B-12-1207.2

"Occupiable spaces and corridors shall have a ceiling height of not less than 7'-6" above the finished floor"

However, immediately following that note; the code then lists a few "Exceptions" to meeting this requirement. Exception #2 would apply to your condition:
"Within a dwelling unit or sleeping unit in a Group R occupancy, habitable spaces and hallways shall have a ceiling height of not less than 7' above the finished floor. Bathrooms, toilet rooms, and laundry rooms shall have a ceiling height of not less than 6'-8" above the finished floor"

Additionally, in th following paragraph 1207.2.1; it also notes an exception for similar residential conditions which allows "Furred Ceilings" (Ductwork, Structural Beams, etc) to be permitted as low as 6'-4".

In Short; the Diagram you posted indicates the correct conditions that would apply to your residential basement. (Assuming this is a residential building)

Hope this helps to clarify things for you. Feel free to reach out to me directly if you have any other questions or would like to discuss a few other concerns you may run into during your remodel to Duplex your 1st floor unit into th basement.

Jonathan Klemm · Answer

Hey @Abby S. - Chicago zoning & permitting is always a confusing topic.  @Prashanth Mahakali or @Samuel Pavlovcik are always good bets to figure these types of questions out.

John Warren · Answer

@Abby S. when you get to this level of detail, you will want to check in with an architect to be honest. @Prashanth Mahakali might be able to help here.

Nilusha Jayasinghe · Answer

Hi @Samuel Pavlovcik, I know this is an old thread but it’s relevant to what I’m going through right now as I’m thinking of establishing a duplex down into my nonconforming basement and have a question about ceiling height. I spoke with the Dept of Buildings and they actually referenced 14X, not 14B since this is an existing building. In 14X, it says that the ceiling height within a dwelling unit (like in the basement of a duplex down) can be 6’8” and if there are beams/other obstructions that cover <25% of the area, those areas can be min 6’0”. Are you able to clarify if the measurements written in 14B that you mentioned should actually be used instead of these and if so, why? Thank you so much!!

Abby S. · Answer

This directionally feels like great news, and appreciate the detailed input!

Jonathan Klemm · Answer

@Samuel Pavlovcik - Thank you for posting.  This helped me a ton too.  Chicago basements/adu's are so tough to understand.

Have you had any instances where some areas were slightly under 7' and inspectors made the owner/contractor rip out the floor because it was not adequate?

Chicago basement ceiling height: 7'6" or 7'?

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