Exit stairway at top floor fire separation

[sunyaer]

I have two questions regarding exit stairway at top floor fire separation, here is the file:

Exit stairs fire resistance rating there is no floor assembly above.pdf

Shared with Dropbox

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1st question : what is the required fire resistance rating of the roof over the stairway at the top floor?
2nd question: is "there is no floor assembly above" true at the top floor (3rd floor in the file)?

 

[tmurray]

1. Roof rating would be contained in the building classification under 3.2.2.

2. Correct. First thing you need to do is figure out the 3.s.s classification for the building. You need to look at three instances as it have 3 major occupancies and take the most restrictive. The rating required for the floor will apply to the whole wall shared with the remainder of the building.

Exit enclosures are treated very different as you cannot penetrate the exit enclosure for anything that does not directly serve the exit. You need to think about them as their own little box from a fire separation perspective.

 

[Inspector Gadget]

Exit enclosures are treated very different as you cannot penetrate the exit enclosure for anything that does not directly serve the exit. You need to think about them as their own little box from a fire separation perspective.

I find this has been a challenge in Part 9 buildings, because the average house-builder wants to build an 8' exit wall with a double top plate to support floor joists, even when I've specifically delayed a permit until plans show a breakout with a ledger through 5/8 Type X drywall.

 

[tmurray]

I find this has been a challenge in Part 9 buildings, because the average house-builder wants to build an 8' exit wall with a double top plate to support floor joists, even when I've specifically delayed a permit until plans show a breakout with a ledger through 5/8 Type X drywall.

We had the same issue when I started. Sometimes it is not the new requirements that get you, it's the ones that have always been there but not enforced.

 

[sunyaer]

I find this has been a challenge in Part 9 buildings, because the average house-builder wants to build an 8' exit wall with a double top plate to support floor joists, even when I've specifically delayed a permit until plans show a breakout with a ledger through 5/8 Type X drywall.

Would a simple sketch be available to show this?

 

[steveray]

Exit enclosures are treated very different as you cannot penetrate the exit enclosure for anything that does not directly serve the exit. You need to think about them as their own little box from a fire separation perspective.

The more I learn about Canada, the more I love it....."ICC" has given up on this as the builders and designers thought it was too hard...

 

[tmurray]

The more I learn about Canada, the more I love it....."ICC" has given up on this as the builders and designers thought it was too hard...

Once you work through it with a contractor and they can figure out the order work in this area has to be done in, you are good to go.

 

[Inspector Gadget]

Would a simple sketch be available to show this?

 

[Inspector Gadget]

The more I learn about Canada, the more I love it....."ICC" has given up on this as the builders and designers thought it was too hard...

Dunno why. It's not complicated.

 

[sunyaer]

I find this has been a challenge in Part 9 buildings, because the average house-builder wants to build an 8' exit wall with a double top plate to support floor joists, even when I've specifically delayed a permit until plans show a breakout with a ledger through 5/8 Type X drywall.

Where is (plans show) a breakout with a ledger through 5/8 Type X drywall? Is there a penetration because of that?

 

[Inspector Gadget]

Where is (plans show) a breakout with a ledger through 5/8 Type X drywall? Is there a penetration because of that?

Only fasteners.

 

[sunyaer]

I find this has been a challenge in Part 9 buildings, because the average house-builder wants to build an 8' exit wall with a double top plate to support floor joists, even when I've specifically delayed a permit until plans show a breakout with a ledger through 5/8 Type X drywall.

What does this have to do with penetration?

 

[Inspector Gadget]

What does this have to do with penetration?

If you have flooring members supported by the top plates of what is supposed to be an exit, the joists are compromising the integrity of the fire-rated drywall.

9.9.4.2(4)
"A fire separation that separates an exit from the remainder of the building shall
have no openings except those for electrical wiring, noncombustible conduit and
noncombustible piping that serve only the exit, and for standpipes, sprinkler piping, exit
doorways and wired glass and glass block permitted in Article 9.9.4.3."

 

[sunyaer]

If you have flooring members supported by the top plates of what is supposed to be an exit, the joists are compromising the integrity of the fire-rated drywall.

9.9.4.2(4)
"A fire separation that separates an exit from the remainder of the building shall
have no openings except those for electrical wiring, noncombustible conduit and
noncombustible piping that serve only the exit, and for standpipes, sprinkler piping, exit
doorways and wired glass and glass block permitted in Article 9.9.4.3."

That's for sure, the joists framing into the drywall would be acting as fire spreading bridge, correct?

 

[Inspector Gadget]

That's for sure, the joists framing into the drywall would be acting as fire spreading bridge, correct?

Well, they act as a penetration of the fire-rated assembly.
I can't tell you how often I've run into this issue.

 

[sunyaer]

Well, they act as a penetration of the fire-rated assembly.
I can't tell you how often I've run into this issue.

It would not be quite often, but there is a chance for that to happen.

 

[steveray]

2021 IBC...

1023.5 Penetrations. Penetrations into or through interior
exit stairways and ramps are prohibited except for the
following:
1. Equipment and ductwork necessary for independent
ventilation or pressurization.
2. Fire protection systems.
3. Security systems.
4. Two-way communication systems.
5. Electrical raceway for fire department communication
systems.
6. Electrical raceway serving the interior exit stairway
and ramp and terminating at a steel box not exceeding
16 square inches (0.010 m2).
7. Structural elements supporting the interior exit stairway
or ramp or enclosure, such as beams or joists.

Such penetrations shall be protected in accordance with
Section 714. There shall not be penetrations or communication
openings, whether protected or not, between adjacent
interior exit stairways and ramps.

Exception: Membrane penetrations shall be permitted on
the outside of the interior exit stairway and ramp. Such
penetrations shall be protected in accordance with Section
714.4.2.

 

[Inspector Gadget]

2021 IBC...

1023.5 Penetrations. Penetrations into or through interior
exit stairways and ramps are prohibited except for the
following:
1. Equipment and ductwork necessary for independent
ventilation or pressurization.
2. Fire protection systems.
3. Security systems.
4. Two-way communication systems.
5. Electrical raceway for fire department communication
systems.
6. Electrical raceway serving the interior exit stairway
and ramp and terminating at a steel box not exceeding
16 square inches (0.010 m2).
7. Structural elements supporting the interior exit stairway
or ramp or enclosure, such as beams or joists.

Such penetrations shall be protected in accordance with
Section 714. There shall not be penetrations or communication
openings, whether protected or not, between adjacent
interior exit stairways and ramps.

Exception: Membrane penetrations shall be permitted on
the outside of the interior exit stairway and ramp. Such
penetrations shall be protected in accordance with Section
714.4.2.

Interesting. So IBC has an exception that NBC (Canada) does not.