1-HR BEARING WALL IN VA: PROTECT STUDS AT DOOR OPENINGS? Not a fire barrier, fire partition or fire wall

[steveray]

Another way to think about it:
- A one hour wood-framed structural wall has to keep the structure from collapsing for one-hour (Table 602).
- A one hour separation wall (such as for occupancy separation, separating corridors from dwelling units, etc.) needs to both remain standing, and prevent burn-through for one hour. Another way to think about it is that it gets about 30 minutes to get to the center of the wall.
- OK, IBC table 723.6.2 says that in a typical wood wall where studs are 16" O/C, the studs themselves are good for 20 minutes of fire protection.
- Now imagine 2 studs butted against each other

And I am absolutely good with that....But when the first stud is the jack stud holding up X000 pounds.....Or there is no jack stud and there is a metal hanger carrying the header....And they pad out the header with plywood to match the 3.5" wall....With gaps in it....Something needs to keep the fire away from the structure.

That is why I said there are alternatives to protect the framing....What I will not say is that you do not have to protect the "exposed" structural framing in the building in VA construction...

 

[redeyedfly]

So by your idiot logic,

By thousands of feet of FRR bearing/exterior walls I've built which did not wrap the jambs. The code does not require it.
You could try you ridiculous single stud scheme but that doesn't meet the intent. Unprotected openings in bearing walls are ok because they are redundant repetitive member assemblies. You can lose the members at the edges of the openings and still not collapse in most situations. That is why they are classified as secondary structural. Secondary structural does not require full encasement. You guys need to stop and think about why the code treats these different assemblies and structural elements differently.

I did once have an inspector insist that the jambs be wrapped, he was laughed out of his own building department.

 

[steveray]

Secondary structural does not require full encasement.

You are right...it is allowed to be protected by the membrane of the wall covering....Which is gypsum.....Individual encasement is covered in 704.2 and .3, we are speaking of 704.4...."I've done it this way for 30 years so it must be right" Awesome logic you have there...That is the same logic that now allows exit enclosures to be penetrated like swiss cheese.....Let me put this one more way and then I am going to give up, You have a 16' long girder truss as a header in an "opening"....That bottom chord of a 2X4 needs no protection on it and can be directly exposed to fire because it is an opening?

 

[redeyedfly]

.Let me put this one more way and then I am going to give up, You have a 16' long girder truss as a header in an "opening"....That bottom chord of a 2X4 needs no protection on it and can be directly exposed to fire because it is an opening?

Wow, no that would be insane. And it demonstrates how you don't understand the logic of the different assemblies in ch. 7.

A truss is dealt with explicitly, 2018 IBC 704.5. The bottom chord of a truss is fracture critical. A bottom truss chord and a bearing wall stud (or trimmer even) are about as far apart structurally as two sticks can be.

A typical bearing wall could lose 50% of the members and still not fail at design load. That's why you only need to put gypsum panels on the sides of a bearing wall and you're done, and you have to wrap trusses in a UL (or some other tested) assembly which require full encasement. See also 711 which sends you to 712 that covers penetrations and openings. See also, columns and beams attached to columns. Primary structural is completely different than very redundant repetitive member bearing wall designs. Trusses are fully wrapped and bearing walls are not (and penetrations don't need to be firestopped!).

If it makes you feel better, you still have protection with the char factor on the exposed wood. Any trimmers required for a non-negligible header load can certainly lose one of the trimmers (~1 hr FRR/1 1/2" wood). and still meet the capacity required in a fire event. If you're requiring this as a BO you are contributing to the high cost of housing and providing no safer buildings. Ch. 7 is very well thought out and based on sound engineering to ensure compartmentalization of smoke and fire and adequate fire resistance at structural members to allow time for people to evacuate in a fire event.

 

[steveray]

OK.... so you want to argue semantics (my bad example using truss)....Insert any light frame element in that situation....a doubled I-joist with a bearing wall above, plywood box header, any header whatsoever and the things that are allowed to hold them up, etc...the intent is to preserve the structure...I understand how repetitive frame works, and the safety factor built in....Headers and their supports and other items that frame openings are not the same as light repetitive framing.....

 

[Yikes]

Looks like we've covered this ground previously, with similar results:

https://www.thebuildingcodeforum.com/forum/threads/protection-of-structural-frame-at-unprotected-openings-in-bearing-walls.10293/

 

[Blazer]

Jack studs (structural member) supporting the header for a door opening do not require individual protection where protected by membrane provided for wall because it is a "boundary element". A door jamb is a membrane. Whether you disagree or not, last time I checked the code never defines what materials can be considered a membrane. Can be any material as stated by 602.5.

 

[steveray]

Jack studs (structural member) supporting the header for a door opening do not require individual protection where protected by membrane provided for wall because it is a "boundary element". A door jamb is a membrane. Whether you disagree or not, last time I checked the code never defines what materials can be considered a membrane. Can be any material as stated by 602.5.

The "membrane" that provides the bearing wall protection is the drywall......I do agree that the jamb MAY be equivalent, but someone needs to quantify that, and the protection needs to be there...Again, by your 602.5 logic, the membrane could be Sterno and you would be OK with that....