Stair shaft top

[meg]

I'm using IBC 2018 and I have a stair shaft that is pre-cast 2 hour fire rated that extends beyond the roof of the attached building. According to 713.12 it only needs to be rated if it doesn't extend to the underside of the roof sheathing, deck or slab. Since it extends beyond that structure, does the roof need to be rated?

 

[RLGA]

It only needs to be rated if the construction type requires a rated roof assembly.

 

[classicT]

Agree with Ron...

In looking for the code reference, see the following:

713.12 Enclosure at Top
A shaft enclosure that does not extend to the underside of the roof sheathing, deck or slab of the building shall be enclosed at the top with construction of the same fire-resistance rating as the topmost floor penetrated by the shaft, but not less than the fire-resistance rating required for the shaft enclosure.

713.5 Continuity
Shaft enclosures shall be constructed as fire barriers in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 711, or both, and shall have continuity in accordance with Section 707.5 for fire barriers or Section 711.2.2 for horizontal assemblies, as applicable.

707.5 Continuity
Fire barriers shall extend from the top of the foundation or floor/ceiling assembly below to the underside of the floor or roof sheathing, slab or deck above and shall be securely attached thereto. Such fire barriers shall be continuous through concealed space, such as the space above a suspended ceiling. Joints and voids at intersections shall comply with Sections 707.8 and 707.9.

Exceptions:​

1. Shaft enclosures shall be permitted to terminate at a top enclosure complying with Section 713.12.
2. Interior exit stairway and ramp enclosures required by Section 1023 and exit access stairway and ramp enclosures required by Section 1019 shall be permitted to terminate at a top enclosure complying with Section 713.12.
3. An exit passageway enclosure required by Section 1024.3 that does not extend to the underside of the roof sheathing, slab or deck above shall be enclosed at the top with construction of the same fire-resistance rating as required for the exit passageway.

Note that a rated roof is only required where terminating below the roof (i.e. shaft does not extend to roof deck) or where required per IBC Table 601.

 

[e hilton]

If the shaft is precast walls, wouldn’t there be a precast piece to form the roof?

 

[RLGA]

If the shaft is precast walls, wouldn’t there be a precast piece to form the roof?

In most cases, no. Many precast buildings (typically tilt-up) use conventional construction for roof and floor construction, such as steel beams, joists, and metal decking.

 

[meg]

I'm using IBC 2018 and I have a stair shaft that is pre-cast 2 hour fire rated that extends beyond the roof of the attached building. According to 713.12 it only needs to be rated if it doesn't extend to the underside of the roof sheathing, deck or slab. Since it extends beyond that structure, does the roof need to be rated?

It only needs to be rated if the construction type requires a rated roof assembly.

It connects a IB garage with a VB apartments. If we consider it the VB, the roof isn't required to be rated.

 

[meg]

Agree with Ron...

In looking for the code reference, see the following:

713.12 Enclosure at Top
A shaft enclosure that does not extend to the underside of the roof sheathing, deck or slab of the building shall be enclosed at the top with construction of the same fire-resistance rating as the topmost floor penetrated by the shaft, but not less than the fire-resistance rating required for the shaft enclosure.

713.5 Continuity
Shaft enclosures shall be constructed as fire barriers in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 711, or both, and shall have continuity in accordance with Section 707.5 for fire barriers or Section 711.2.2 for horizontal assemblies, as applicable.

707.5 Continuity
Fire barriers shall extend from the top of the foundation or floor/ceiling assembly below to the underside of the floor or roof sheathing, slab or deck above and shall be securely attached thereto. Such fire barriers shall be continuous through concealed space, such as the space above a suspended ceiling. Joints and voids at intersections shall comply with Sections 707.8 and 707.9.

Exceptions:​

1. Shaft enclosures shall be permitted to terminate at a top enclosure complying with Section 713.12.
2. Interior exit stairway and ramp enclosures required by Section 1023 and exit access stairway and ramp enclosures required by Section 1019 shall be permitted to terminate at a top enclosure complying with Section 713.12.
3. An exit passageway enclosure required by Section 1024.3 that does not extend to the underside of the roof sheathing, slab or deck above shall be enclosed at the top with construction of the same fire-resistance rating as required for the exit passageway.

Note that a rated roof is only required where terminating below the roof (i.e. shaft does not extend to roof deck) or where required per IBC Table 601.

Thanks. That is what I thought but wanted to get a second option.

 

[Paul Sweet]

Does it extend into the VB apartments? If so the rated shaft needs to extend through the apartments to the apartment roof, or have a rated cap.