Penetrations of FRR Load Bearing Walls

[steveray]

704.2 exception sends you to 704.4.1

Got it..don't have that yet...Still don't think I am calling a king or jack a column though...

 

[redeyedfly]

Got it..don't have that yet...Still don't think I am calling a king or jack a column though...

Jack is definitely a column. It is the member that supports the header.
This discussion exemplifies the need for the clarification they made in 2018.

 

[steveray]

First, I'm referencing 2018.

The enclosure does start at the beginning of the rating but 1023.5 is limiting penetrations that go into the stairway. Again, the intent is to keep anything unrelated to the shaft out of the shaft. They don't want pipes or anything else running into the stairway and then back out that don't serve the stairway. There is no prohibition of penetrations that serve the stairway, like beams supporting the landings.

You don't need to prevent landing penetrating your shaft is they have the same rating as the shaft. They ARE part of the shaft. Shafts don't need to be straight, they can jog, go sideways, go at an angle, whatever. They only need to maintain a continuous rated enclosure. Again, the PT example; there are thousands of PT buildings with mid floor landing that are hung from the slab above with hanging columns inside the shaft wall and beams that penetrate the inside of the shaftwall (firestopped) to connect to the hanging column. That is the typical detail. It is, and always has been, acceptable under IBC.

So again, you are OK with a light frame truss 1 hour floor system, via platform framing, penetrating the 1 hour exit enclosure and cantilevering in to become the landing because it is 1 hour rated and "supports" the stair?. Even though that assembly is not protected anywhere near a fire barrier throughout the other areas of the building it serves? Or are you saying that only individual penetrations are allowed even though that is not how the code reads?

I agree with you on the noncombustible buildings (PT) you keep referencing this is less of an issue, I just see this as a huge issue in a 3 story VA 13 R building

 

[steveray]

Jack is definitely a column. It is the member that supports the header.
This discussion exemplifies the need for the clarification they made in 2018.

So then I will go back to this:

704.4.1 Light-frame construction. Studs, columns and
boundary elements that are integral elements in walls of lightframe
construction and are located entirely between the top
and bottom plates or tracks shall be permitted to have
required fire-resistance ratings provided by the membrane
protection provided for the wall.

And say that the headers (door headers certainly are not between the top and bottom plates.....Which I assume the intent is compartmentation to minimize fire/ heat exposure like you would in a stud cavity....

 

[redeyedfly]

So again, you are OK with a light frame truss 1 hour floor system, via platform framing, penetrating the 1 hour exit enclosure and cantilevering in to become the landing because it is 1 hour rated and "supports" the stair?. Even though that assembly is not protected anywhere near a fire barrier throughout the other areas of the building it serves? Or are you saying that only individual penetrations are allowed even though that is not how the code reads?

I agree with you on the noncombustible buildings (PT) you keep referencing this is less of an issue, I just see this as a huge issue in a 3 story VA 13 R building

I'm ok with it not because it supports the stair but because it is a 1hr horizontal assembly. It IS the shaft. See 713.2 fire barriers AND horizontal assemblies enclose the shaft. The only test is that you can draw an unbroken line entirely around the shaft and maintain the rating with fire barriers and horizontal assemblies. The requirements for horizontal assemblies is nearly identical to fire barriers.

 

[redeyedfly]

So then I will go back to this:

704.4.1 Light-frame construction. Studs, columns and
boundary elements that are integral elements in walls of lightframe
construction and are located entirely between the top
and bottom plates or tracks shall be permitted to have
required fire-resistance ratings provided by the membrane
protection provided for the wall.

And say that the headers (door headers certainly are not between the top and bottom plates.....Which I assume the intent is compartmentation to minimize fire/ heat exposure like you would in a stud cavity....

Yeah, I think solid headers should be included. In practice I have not encountered a BO who requires individual encasement of headers.

I think the original intent and the intent of the 2018 clarification is that light frame repetitive member assemblies are very redundant and the gyp membranes are adequate to protect the structure. Load bearing wall protection is far different from fire barriers and fire partitions which are designed to compartmentalize the fire in the building to reduce the spread. It is a much lower standard to meet.

 

[steveray]

I'm ok with it not because it supports the stair but because it is a 1hr horizontal assembly. It IS the shaft. See 713.2 fire barriers AND horizontal assemblies enclose the shaft. The only test is that you can draw an unbroken line entirely around the shaft and maintain the rating with fire barriers and horizontal assemblies. The requirements for horizontal assemblies is nearly identical to fire barriers.

Quiet in here except for us......Yeah, but....the horizontal assembly can have hundreds or penetrations in it "feeding into" the exit enclosure, bypassing the "serving the/ or necessary for enclosure" provision, lights, HVAC registers, bearing walls etc.. all penetrate the ceiling membrane in the corridors and dwelling units that will now have a direct line into the exit enclosure. In theory they are mostly rated penetrations, but in my opinion putting the exit enclosure at unnecessary risk. If we are going down this road, we just need to delete all limitations to penetrations....

 

[steveray]

Maybe someone will link up that change info....i'd like to see that reasoning...I watched the exit enclosure penetration one and it was basically "that is how everyone is building them anyway so we should just allow it".....