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Penetrations of FRR Load Bearing Walls

R

redeyedfly

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Feb 22, 2021
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Minneapolis, MN
I have a building official that is insisting that FRR load bearing walls must have protected membrane penetrations. (2018 IBC)

The specific issue is a data center box inset into the wall. The BO insists that 704.4.1 requires all exposed wood to be covered by gyp. His argument: "There is no subsection within this part that allows openings or penetrations in this membrane protection." My argument is that there is no requirement to provide opening or membrane penetration protection. 714.4 does not list bearing walls. Nothing sends you to 716.

ICC commentary: “Although a building element is required to have fire resistance by Table 601, this does not mean that the required openings in these building elements have to be protected.” It goes on to state “For example, an interior bearing wall inside a Type IIA building is required to have a fire-resistance rating of not less than 1 hour. However, the openings in that wall need not be protected.”

The ICC opinion we requested said essentially the same as the commentary.

I have never heard of this interpretation. It would follow that all load bearing exterior walls would require membrane penetration by his interpretation of 704.4.1. All window and door openings would need to be wrapped in gyp.

This interpretation seems to misunderstand the different types of FRR assemblies and their purpose.

Any help for a final argument before we appeal to the state is appreciated.
 
Is the wood exposed, or is it covered by the box? If covered by the box, as you said, it is not any different that a window.

Also, is the penetration in the interior or exterior membrane? If on the exterior and the wall is more than 10 feet from the lot line, then the wall is only required to be protected from an interior exposure and the outside membrane is irrelevant.
 
The specific condition is in an interior load bearing wall that is not required to be rated for any other reason than it is a load bearing wall (side wall of a closet entirely surrounded by the same unit). The wood is covered by the box but I don't see how that would make a difference. There are no requirements to provide opening or membrane penetration protection in the code for load bearing walls. He's arguing that since it isn't specifically allowed, you can't do it. That just isn't how code works; the code tells you what you can't do and what you must do. It would be impossible to exhaustively list all the things you are allowed to do in building design.

I mentioned exterior walls because this interpretation would lead to the same requirement for exterior bearing walls. The code is silent on membrane penetrations of exterior walls too; they only require protection of joints when the FSD is less than 5'.
 
The problem/ question is how is the structure rating maintained if you have basically exposed framing....I would not worry too much about outlet boxes, but large holes with little protection for the structure are another concern...
 
The attached apartment plan from a four-story building has four non-rated wood doors in a bearing wall. There is no gypsum board in the opening.
 

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steveray said:
The problem/ question is how is the structure rating maintained if you have basically exposed framing....I would not worry too much about outlet boxes, but large holes with little protection for the structure are another concern...
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Where in the code is that required? See 602.1
 
The building elements shall have a fireresistance
rating not less than that specified in Table 601 and
exterior walls shall have a fire-resistance rating not less than
that specified in Table 602.

FIRE-RESISTANCE RATING. The period of time a building
element, component or assembly maintains the ability to
confine a fire, continues to perform a given structural function,
or both, as determined by the tests, or the methods based
on tests, prescribed in Section 703.

So I assume there is a test of wood frame structure protected by a vinyl window somewhere?
 
steveray said:
So I assume there is a test of wood frame structure protected by a vinyl window somewhere?
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I've never seen one. What about the 1/2" particle board jambs which according to this BO must be providing equivalent protection of 5/8" Type X.

602.1: The protection of openings, ducts and air transfer openings in building elements shall not be required unless required by other provisions of this code.

No other part of the code requires protection for bearing walls that are not exterior or part of another FRR assembly.
 
So stepping back from the code, let's think about the logic here...

If the load bearing wall has a metal box, a window, a door, whatever type of opening, then the stud adjacent to said opening is not always wrapped in GWB. For windows, I would say that it is typical to wrap up to the frame of the window, but with doors you just run the GWB tight to the door buck. Boxes or ducts penetrating the membrane do just that, and are just a section of wall missing GWB.

Now, given that the GWB is essentially what gives the wall its fire resistance, let us think about a fire situation and what will burn away/be damaged during the fire. As a load bearing wall, it is obviously made up of a repeating framing member. If the one or two members that frame out the opening burn out, is the wall going to fail? No; therefore, I agree that the opening need not typically be wrapped in GWB.

That said, I will reserve that my stance only pertains to conventional light-frame construction. Where you have a column supporting a big point load, or the building is of Type I or Type II construction, then I would tend to go back towards requiring that the end of the wall be wrapped/fully encased. See 704.2-704.4 where it speaks of individual encasement.
 
classicT said:
So stepping back from the code, let's think about the logic here...

If the load bearing wall has a metal box, a window, a door, whatever type of opening, then the stud adjacent to said opening is not always wrapped in GWB. For windows, I would say that it is typical to wrap up to the frame of the window, but with doors you just run the GWB tight to the door buck. Boxes or ducts penetrating the membrane do just that, and are just a section of wall missing GWB.

Now, given that the GWB is essentially what gives the wall its fire resistance, let us think about a fire situation and what will burn away/be damaged during the fire. As a load bearing wall, it is obviously made up of a repeating framing member. If the one or two members that frame out the opening burn out, is the wall going to fail? No; therefore, I agree that the opening need not typically be wrapped in GWB.

That said, I will reserve that my stance only pertains to conventional light-frame construction. Where you have a column supporting a big point load, or the building is of Type I or Type II construction, then I would tend to go back towards requiring that the end of the wall be wrapped/fully encased. See 704.2-704.4 where it speaks of individual encasement.
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I agree 100%
 
What if the "single member" is the bottom chord of a truss used as a header? supporting multiple members? This is a bit of a hole in VA stuff that ICC should clarify... Protection of "openings" for fire spread vs. protection of structures...

The discomfort I have is that I could have an exposed "bottom chord" 8' truss header or plywood box header with absolutely no protection....
 
steveray said:
What if the "single member" is the bottom chord of a truss used as a header? supporting multiple members? This is a bit of a hole in VA stuff that ICC should clarify... Protection of "openings" for fire spread vs. protection of structures...

The discomfort I have is that I could have an exposed "bottom chord" 8' truss header or plywood box header with absolutely no protection....
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704.4.1 may need another revision. As it reads now that truss would require individual protection since it isn't a stud, column, or boundary element. But I don't think a solid header within a wall should require individual protection. If challenged on a solid header without individual encasement (I never have) I would probably give them a char calc. There is almost always a lot of extra capacity in scheduled dimensional headers.

In my current specific situation the exposed members are repetitive studs. 602.1 & 714.4 tell me openings and membrane penetrations do not require protection in load bearing walls. I believe it's a membrane penetration by definition. The BO is using opening and penetration interchangeably which is very telling of his understanding of FRRs. He is claiming 704.4.1 requires the membrane to fully encapsulate the wall... but not at doors or windows or service panels, just the data box. The UL listing does not require it and the code specifies clearly which FRR assys require protection of openings and penetrations; load bearing walls ain't in there.
 
Again...what if it is a "single king" with a hanger.....As much as I hate "what if", this is kind of an all of nothing area at this point....Especially now that we are easing up on stair penetrations, all of these "unrated" cracks, gaps, etc are going to feed into the exit enclosures at some point.....

1619713567785.png
 
A king stud is a column and is specifically mentioned in 714.4 to be protected by the wall membrane.

I have no idea what point you're trying to make about stair shafts. Those are fire barriers and require both protected openings and penetrations. The only easing up was allowing penetrations on the exterior membrane. You still need a penetration firestop if you exceed the exceptions in 714.4.2. You have ALWAYS been allowed to penetrate the shaft walls with structural elements that support the stair.
 
Not in CT.....And this will now allow I joists or open web trusses to penetrate and become the landing cantilever with not firestopping what so ever as th floor ceiling assembly has the same rating as the exit enclosure.....With shafts you could, but not with exit enclosures....Different....
 
steveray said:
Not in CT.....And this will now allow I joists or open web trusses to penetrate and become the landing cantilever with not firestopping what so ever as th floor ceiling assembly has the same rating as the exit enclosure.....With shafts you could, but not with exit enclosures....Different....
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You can have floor assemblies project into stair shafts if they have the same or higher rating. Think of a landing in a PT concrete building. Enclosures for stairs are to be constructed of fire barriers OR horizontal assemblies. Typical shafts in concrete buildings are infill walls between the slabs or spandrel beams. 100% OK.

I think you're confusing the intent of 1023.5. It isn't discussing penetrations of the fire barrier or horizontal assemblies of the shaft but the stairway itself. 707.7.1 further reinforces the intent prohibiting "Penetrations into enclosures". The intent is that you can't have anything unrelated to the shaft penetrate the stairway. You can have a beam penetrate the membrane for a landing inside the shaft. It must be firestopped but it is allowed and always has been in my recollection.
 
Thank You for the discussion BTW.....

Well 704 only applies to secondary members which columns would not be...And the headers would be "directly attached"....

SECONDARY MEMBERS. The following structural members
shall be considered secondary members and not part of
the primary structural frame:
1. Structural members not having direct connections to
the columns.
2. Members of the floor construction and roof construction
not having direct connections to the columns.
3. Bracing members other than those that are part of the
primary structural frame.

And I would argue that they are not protected by the wall membrane if they are protected by a jack stud, it might be equivalent, but that is a different argument...
 
redeyedfly said:
I think you're confusing the intent of 1023.5. It isn't discussing penetrations of the fire barrier or horizontal assemblies of the shaft but the stairway itself. 707.7.1 further reinforces the intent prohibiting "Penetrations into enclosures". The intent is that you can't have anything unrelated to the shaft penetrate the stairway. You can have a beam penetrate the membrane for a landing inside the shaft. It must be firestopped but it is allowed and always has been in my recollection.
Click to expand...

I would argue no as written....in 2015

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
714.3.2.

I would argue that the "enclosure" starts at the beginning of the rating and No penetrations are allowed on the inside per the exception.....Which again, makes no sense to me...But may be the route I need to go to prevent the situation with the cantilevered landing penetration...
 
steveray said:
Thank You for the discussion BTW.....

Well 704 only applies to secondary members which columns would not be...And the headers would be "directly attached"....

SECONDARY MEMBERS. The following structural members
shall be considered secondary members and not part of
the primary structural frame:
1. Structural members not having direct connections to
the columns.
2. Members of the floor construction and roof construction
not having direct connections to the columns.
3. Bracing members other than those that are part of the
primary structural frame.

And I would argue that they are not protected by the wall membrane if they are protected by a jack stud, it might be equivalent, but that is a different argument...
Click to expand...
704 is for all structural members, not just secondary. And 704.4.1 specifically addresses protection of "Studs, columns and boundary elements that are integral elements in walls of light-frame construction" as protected by the wall membrane. The jack stud is actually the column supporting the header, not the king, sorry for the error above. There's no need to argue anything, the code made it clear in 2018.
 
steveray said:
I would argue no as written....in 2015

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
714.3.2.

I would argue that the "enclosure" starts at the beginning of the rating and No penetrations are allowed on the inside per the exception.....Which again, makes no sense to me...But may be the route I need to go to prevent the situation with the cantilevered landing penetration...
Click to expand...
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.
 
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