When does a protected opening become too big to be considered an opening?

[nealderidder]

I brought this up in another thread: Lightwell Shaft with Fire Shutters

But I think the question got lost in the bigger issue.

I'm looking at a "shaft" that is basically a light well at the top of an atrium. I met with the AHJ and we concluded that a 2 hr fire barrier is required around the perimeter of the light well at the 3rd and 4th floors.

So what is that barrier? They were OK with rated storefront (pricey) but balked at the idea of non-rated storefront with a fire shutter, didn't like the idea of non-passive protection.

If the barrier were a solid wall with a 4'x4' opening protected by a shutter it would probably be OK? Is it the fact that the size of the "shutter" is 95% of the size of the "barrier" the troublesome thing here?

To get to an actual question - do you think non-rated storefront with a fire shutter (maybe a Won-Door movable fire wall) is a legit solution to providing a 2hr barrier around this shaft? See attached.

Thanks,

 

[RLGA]

See IBC (2018) Section 404.6, Exception 1.

 

[cda]

I brought this up in another thread: Lightwell Shaft with Fire Shutters

But I think the question got lost in the bigger issue.

I'm looking at a "shaft" that is basically a light well at the top of an atrium. I met with the AHJ and we concluded that a 2 hr fire barrier is required around the perimeter of the light well at the 3rd and 4th floors.

So what is that barrier? They were OK with rated storefront (pricey) but balked at the idea of non-rated storefront with a fire shutter, didn't like the idea of non-passive protection.

If the barrier were a solid wall with a 4'x4' opening protected by a shutter it would probably be OK? Is it the fact that the size of the "shutter" is 95% of the size of the "barrier" the troublesome thing here?

To get to an actual question - do you think non-rated storefront with a fire shutter (maybe a Won-Door movable fire wall) is a legit solution to providing a 2hr barrier around this shaft? See attached.

Thanks,

what is the height of your glass ???



Plus a good Fire Protection Engineer can help with your design.
And probably save you money and headaches


Do you own the building or designing for it???

 

[nealderidder]

what is the height of your glass ???



Plus a good Fire Protection Engineer can help with your design.
And probably save you money and headaches


Do you own the building or designing for it???

Designing. Just so happen to have a meeting scheduled with the FPE this afternoon.

 

[nealderidder]

See IBC (2018) Section 404.6, Exception 1.

I tried that. The AHJ's conclusion was that this only applies if the skylight shaft is a part of the atrium. And if the shaft is part of the atrium they would consider the atrium "connecting" more than 2 stories and smoke control wold be required (and there goes any cost savings).

 

[RLGA]

I tried that. The AHJ's conclusion was that this only applies if the skylight shaft is a part of the atrium. And if the shaft is part of the atrium they would consider the atrium "connecting" more than 2 stories and smoke control wold be required (and there goes any cost savings).

In that case, you have to provide 2-hour fire barriers with a 2-hour horizontal assembly between the 2nd and 3rd stories, which means the 2-hour horizontal assembly will need to be supported by 2-hour construction.

Per Table 716.1(2), only fire-resistive glazing is permitted. Fire shutters are permitted but must be rated for 1.5 hours.and would be limited to 25% of the fire barrier's length.

 

[RLGA]

Another option...

Smoke control can be of any option mentioned in Section 909 and doesn't have to be mechanical exhaust. If the 3rd and 4th stories are not open to the atrium and are designed as smoke barriers, then that creates a smoke pocket. On the roof provide smoke vents that will naturally ventilate the atrium to keep the smoke accumulation 6 feet above the 2nd story walking surface. This will require the efforts of an FPE to model the conditions to determine the size of ventilation openings and airflow needed.

Think of it like a fly tower above a stage in a theater.

 

[nealderidder]

In that case, you have to provide 2-hour fire barriers with a 2-hour horizontal assembly between the 2nd and 3rd stories, which means the 2-hour horizontal assembly will need to be supported by 2-hour construction.

Per Table 716.1(2), only fire-resistive glazing is permitted. Fire shutters are permitted but must be rated for 1.5 hours.and would be limited to 25% of the fire barrier's length.

Which all brings me back to 2hr glazing. Oh well, it's not my money, right? That 25% is what I was looking for, where did that come from for fire shutters?

 

[nealderidder]

Another option...

Smoke control can be of any option mentioned in Section 909 and doesn't have to be mechanical exhaust. If the 3rd and 4th stories are not open to the atrium and are designed as smoke barriers, then that creates a smoke pocket. On the roof provide smoke vents that will naturally ventilate the atrium to keep the smoke accumulation 6 feet above the 2nd story walking surface. This will require the efforts of an FPE to model the conditions to determine the size of ventilation openings and airflow needed.

Think of it like a fly tower above a stage in a theater.

Now that's an interesting idea. I'll run it by the FPE. Thanks Ron.

 

[cda]

I tried that. The AHJ's conclusion was that this only applies if the skylight shaft is a part of the atrium. And if the shaft is part of the atrium they would consider the atrium "connecting" more than 2 stories and smoke control wold be required (and there goes any cost savings).

Yea you go AHJ

 

[RLGA]

Which all brings me back to 2hr glazing. Oh well, it's not my money, right? That 25% is what I was looking for, where did that come from for fire shutters?

Section 707.6 (2018 IBC)