New Building with Two Non-Continuous Atrium Spaces

[Trivers]

Our designer has created a three-level commercial building on a sloped site that would have two atrium spaces that are not stacked. I'm trying to figure out the code implications for this scenario. We are assuming that we will have to have smoke evac because the three levels are not separated from one another - the spaces are open to each other horizontally at the Main Level circulation space. There are open stairs from Lower Level to Main Level in the lower atrium, and another open stair from the Main Level to the Upper Level in the upper atrium.

I'm assuming the stairs do not need a draft curtain, since in each case they only connect two stories. Is that a correct assumption? Do we need draft curtains at the ceiling of each opening?

 

[steveray]

What is the use?

CT is a little tougher on exit access stairs than ICC...What codes do you use?

 

[Trivers]

What is the use?

CT is a little tougher on exit access stairs than ICC...What codes do you use?

We are designing to the 2021 IBC, as it will be adopted in WI by the time we submit the project for review.

 

[Trivers]

Also, the building is Mixed-Use, non-separated (Assembly A2 most stringent).

 

[steveray]

So....you will want to look at 404.10 and 1028 for sure, but also maybe exit access stairs in 1019...Not really a simple answer without plans....

404.10Exit stairways in an atrium.
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Where an atrium contains an interior exit stairway all the following shall be met:

1. 1.The entry to the exit stairway is the edge of the closest riser of the exit stairway.
2. 2.The entry of the exit stairway shall have access from a minimum of two directions.
3. 3.The distance between the entry to an exit stairway in an atrium and the entrance to a minimum of one exit stairway enclosed in accordance with Section 1023.2 shall comply with the separation required by Section 1007.1.1.
4. 4.Exit access travel distance shall be measured to the closest riser of the exit stairway.
5. 5.Not more than 50 percent of the exit stairways shall be located in the same atrium.