Is it a shaft? an atrium?

[nealderidder]

I'm working on an existing four story office building. The big idea is to open up a two story space (think wide corridor) through the entire building. This two-story common space would connect a southern exterior entry to a northern exterior entry.

Simple enough so far but I'd also like to get some daylight into that two-story space. So pop a couple of large skylights on the roof (16'x16') and build a "shaft" through floors 3 and 4 to connect to the two-story commons.

So is that "shaft" through 3 & 4 a shaft or an atrium?

CBC 713 tells me I need a 2 hour shaft enclosure where connecting 4 stories.

CBC 404 tells me I need smoke control but I can also enclose that shaft with glass at the 3rd and 4th floors if I throw in some extra sprinklers.

I'm thinking atrium and want to surround it with glass but thought I would see if opinions differ.

Thanks,

 

[cda]

So will only two floors be open to each other??

Or more

 

[classicT]

Sounds to me like an atrium at the first and second levels, and then (2) shafts through the 3rd and 4th.

Not a Cali guy, so I'll stay out of the code sections.

 

[nealderidder]

So will only two floors be open to each other??

Or more

1st and 2nd are open to each other. 3rd and 4th will be surrounded by glass so not really "open".

 

[cda]

1st and 2nd are open to each other. 3rd and 4th will be surrounded by glass so not really "open".

Not sure what section in CBC it is but should either be 712.1.9 Two Story Opening.

Not sure if that helps you any???

 

[Paul Sweet]

I'm on the road and don't have access to an IBC, but if I remember correctly from a past project, the separation at the 3rd & 4th floor needs to be at least one hour rated, or greater if required by the construction type. California might have different requirements.