Open Stair abave - enclosed stair below.

[UCinCAT]

State: Kentucky

Building Code Used: 2006 International Building Code with 2007 Kentucky Building Code Supplements

Use Group: B

Construction Type: 2B

Fully Sprinkled

40,248 sf building (13,416 sf per floor)

Building is under construction.

Building has two separate stairs systems providing egress from the building. Both stairs communicate between all floors.

One stair is an enclosed egress stair. (CMU stair enclosure)

The other is an interior “L” shaped stair.

The lower level has (3) means of egress

The First floor has (3) means of egress.

Second Floor has (2) means of egress.

The “L” shaped stair is open from the First Floor to the Second Floor and provides one of two methods of egress from the second floor. (2006 IBC 1020.1 - exception 9.)

Another section of the “L” shaped stair is enclosed from the first floor to the lower level. (This portion of the stair is NOT a required means of egress.)

The fire rated assembly enclosing the stair from the First Floor to the Lower Level is comprised of a fire rated glazing assembly on two sides, and a horizontal shaftwall assembly protecting the stair assembly above. Building inspector is taking exception to the attachment of the fire rated assembly to the stair assembly above it. Inspector's position is that the if the rated assembly is attaching to stair assembly above it, it needs to be protected with the same rating as the wall assembly. (If this is true, where is this requirement found in the code?)

Questions:

Is the “L” shaped stair from the First Floor to the lower level required to be enclosed?

If so, Does the enclosure require a rated assembly?

Can the fire rated assembly enclosing the stair to the lower level attach to the stair assembly above it, without requiring the supporting structure to also be protected?

The intent is for the stringers of the stair to the second floor to be exposed. It also provides the surface to which the stair guardrails are attached.

 

[cda]

So is all this shown on the approved plans???

"""Is the “L” shaped stair from the First Floor to the lower level required to be enclosed?"""

If not enclosed than wouldn't you have opening to three floors ,, not allowed ???

 

[UCinCAT]

So is all this shown on the approved plans???

Yes. All on approved plans.

If not enclosed than wouldn't you have opening to three floors ,, not allowed ???

Open to three floors not permitted is now clear to me...I think.

But, if the stair from 1 to LL is not part of a required egress, does the enclosure require a rating?

 

[cda]

Good question

If not needed or identified as an exit, I wondering if it falls under a shaft?? And shaft requirements

I take there is no rated corridor in the lower level??

 

[UCinCAT]

Good questionIf not needed or identified as an exit, I wondering if it falls under a shaft?? And shaft requirements

I take there is no rated corridor in the lower level??

The only rated cooridor on LL is adjacent to second egress stair. The CMU stair enclosure at that location does not have a direct exit to the exterior. Exit passageway is provided to the door exiting the building. it's one of (3) means of egress from the lower level.

I'm also having a hard time understanding why the inspector is insisting the assembly enclosing the stair from 1 to the LL NOT be mechanically fastened to the stair assembly above. It was detailed on the ConDocs to attach to the underside of the stair treads and stringer. He is saying this can't be done without protecting the stair assembly. Any truth to this? Modifying the attachment details could be very costly to the owner.

 

[JBI]

Lacking a fire resistance rating, there is no 'enclosure' - that's what 'enclosed' means. I think the issue may be the supporting construction for the rated horizontal assembly needs to have, at minimum, the same rating as the horizontal assembly (see last line of text below...)

711.4 Continuity.

Assemblies shall be continuous without openings, penetrations or joints except as permitted by this section and Sections 707.2, 712.4, 713 and 1020.1. Skylights and other penetrations through a fire-resistance-rated roof deck or slab are permitted to be unprotected, provided that the structural integrity of the fire-resistance-rated roof construction is maintained. Unprotected skylights shall not be permitted in roof construction required to be fire-resistance rated in accordance with Section 704.10. The supporting construction shall be protected to afford the required fire-resistance rating of the horizontal assembly supported.