Create Mezzanine Level In Existing Lobby

[CAR]

We have an upcoming client presentation in which they want us to propose design options for their lobby refresh. They basically want us to be as creative as possible, without a budget (for now). The existing lobby has 2 ceiling heights. One idea is to open up the stone walls in the images below, this would create a mezzanine type situation with part of the 2nd floor opened to the lobby. We would also add an open stair to access this second level directly from the lobby. Whether it's having full height glass or a guardrail we're still not sure which way to go. But here's where the code issues come in. I'm looking at the IBC chapter on mezzanines so I can determine if this is allowed by code and how far we can go with it. I was wondering if someone could point me in the right direction as to the other chapters I should be checking out (fire protection, egress, etc). Any issues I should watch out for. If anyone has had any experience with similar projects.

 

[cda]

What year IBC?

Two floors open to each other provision ???

 

[Mr. Inspector]

Depends on what code you are using. I would start with the definition.

 

[steveray]

How big and what is the OL of the mezz?

Oh yeah...And what is going to happen on it?

 

[cda]

Quote from RGLA


“””
A two-story volume is an atrium by definition (see cda's response above). HOWEVER, the best place to start regarding two-story openings is Section 712 on vertical openings rather than going directly to Section 404 for atriums. That Section 712, which includes a reference to Section 404, also includes Section 712.1.9 for two-story openings. If your two-story opening complies with the conditions listed, then compliance with Section 404 is not required. It is still an atrium by definition but is not required to comply with the atrium requirements.

Even if you went the route of Section 404 for atriums, a two-story atrium is not required to comply with the smoke control requirements per Section 404.5, Exception, or the enclosure requirements of Section 404.6 per Exception 3. However, other requirements per Section 404 would be applicable that otherwise would not be applicable if using Section 712.1.9.””

 

[CAR]

Thank you everyone for the responses. To add more context. It's the 2019 Chicago Building Code. Which is based on IBC 2018 (with some Chicago-isms left over from the previous code).

I just got the plans. Will post Sq footage, etc. for reference.

 

[CAR]

What year IBC?

Two floors open to each other provision ???

Quote from RGLA


“””
A two-story volume is an atrium by definition (see cda's response above). HOWEVER, the best place to start regarding two-story openings is Section 712 on vertical openings rather than going directly to Section 404 for atriums. That Section 712, which includes a reference to Section 404, also includes Section 712.1.9 for two-story openings. If your two-story opening complies with the conditions listed, then compliance with Section 404 is not required. It is still an atrium by definition but is not required to comply with the atrium requirements.

Even if you went the route of Section 404 for atriums, a two-story atrium is not required to comply with the smoke control requirements per Section 404.5, Exception, or the enclosure requirements of Section 404.6 per Exception 3. However, other requirements per Section 404 would be applicable that otherwise would not be applicable if using Section 712.1.9.””

Thank you! This was incredibly helpful.

Chicago 2019 (IBC 2018 based).

 

[ADAguy]

I have done two of these i the past, one in 73 with drop down fire doors and one in 97 with water curtains. considered two story space / atrium