IBC Section 404 Atriums

[McB_Architects]

I am working on a code analysis for a project.

We have a two story atrium open to the second floor. Section 404.5 says a smoke control system is not required for atriums that connect only two stories. OK fine.

Section 404.6 calls for atriums be separated from adjacent space by a 1-hr fire barrier. However, exception 3 says a fire barrier is not required between atrium and adjoining spaces of any three floors of the atrium provided such spaces prvided such spaces are accouted for in the design of the smoke control system.

I interpret this to mean that we are not required to provide a smoke control system OR a 1-hr fire barrier. Am I correct in that interpretaton? I'm concerned about the wording for Section 404.6, Exception 3 where it says "...provided such spaces a accounted for in the design of the smoke control system." 404.5 says I'm not requred to have a smoke control system for a two story atrium therefore I do not need to account for its design.

Any clarification/advice would be apprecated.

 

[cda]

Which edition are you using

 

[steveray]

Can you call it a mezzanine?.....It sounds like you are on the correct path, but CDA is right that code edition and other details are very important...

 

[AegisFPE]

Instead of using Exception 5 to Section 708.2, consider Exception 7.

 

[McB_Architects]

which edition are you using

2012 ibc, 2012 ifc

 

[cda]

ok i thought they fixed the atrium problem

 

[mjesse]

I interpret this to mean that we are not required to provide a smoke control system OR a 1-hr fire barrier. Am I correct in that interpretaton? 404.5 says I'm not requred to have a smoke control system for a two story atrium therefore I do not need to account for its design.

I agree with your interpretation.

mj

 

[AegisFPE]

2012 ibc, 2012 ifc

In that case, I recommend considering Section 712.1.8 instead of 712.1.6.

 

[RLM-Architect]

Check NFPA 101 Section 8.6.6 for Communicating Space.

There are 8 items which must be met.

(1) The communicating space does not connect more than three contiguous stories. (ONLY 2 PERMITTED BY IBC)

(2) The lowest or next-to-lowest story within the communicating space is a street floor.

(3) The entire floor area of the communicating space is open and unobstructed, such that a fire in any part of the space will be readily obvious to the occupants of the space prior to the time it becomes an occupant hazard.

(4) The communicating space is separated from the remainder of the building by fire barriers with not less than a 1-hour fire resistance rating, unless one of the following is met:

(a) In buildings protected throughout by an approved automatic sprinkler system in accordance with Section 9.7, a smoke barrier in accordance with Section 8.5 shall be permitted to serve as the separation required by 8.6.6(4).

(b) The requirement of 8.6.6(4) shall not apply to fully sprinklered residential housing units of detention and correctional occupancies in accordance with 22.3.1(2) and 23.3.1.1(2).

(5) The communicating space has ordinary hazard contents protected throughout by an approved automatic sprinkler system in accordance with Section 9.7 or has only low hazard contents. (See 6.2.2.)

(6) Egress capacity is sufficient to allow all the occupants of all levels within the communicating space to simultaneously egress the communicating space by considering it as a single floor area in determining the required egress capacity.

(7)* Each occupant within the communicating space has access to not less than one exit without having to traverse another story within the communicating space.

(8) Each occupant not in the communicating space has access to not less than one exit without having to enter the communicating space.

If you meet them, you will also meet the requirements for 2 story atrium in the IBC.

You can only leave the areas on floors open to the atrium space (IBC) IF AND ONLY IF you provide the smoke removal system.

If building is fully sprinkler protected, only smoke barriers are required otherwise one hour separation is required.

Maybe this helps?

 

[Architect1281]

If every one of us that remembers the old days they used to call a hole in the floor between only 2 stories a Floor Opening

then when it went to a hole in 2 consecutive floors connecting 3 stories that was an atrium, Its the things I look for that are no longer there I find hardest to find.

 

[Codegeek]

For any opening between floors, you must start in Chapter 7, specifically in Section 712 for vertical openings (2012 IBC). If you cannot meet one of the exceptions, then the opening must be protected. An atrium is one of the exceptions. For the atrium, yes if it is only two stories then smoke control is not required. The one hour barrier is not required because the smoke control is not required.

Another exception is listed in 712.1.8. You must meet all 7 criteria for it to qualify as an unprotected opening. You may also qualify under 712.1.12 if you can meet travel distances and have the stair serve as an exit access stair.