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Protection of structural frame at unprotected openings in bearing walls

J

jackbweth

Member
Joined
May 22, 2013
Messages
17
Location
roanoke, va
We have several projects of different construction types with exterior and interior bearing walls that are required to be rated 1 and 2 hours. The walls/partitions are rated for protection of structure only, but have doors and window openings within the bearing wall framing. The question and debate within the office and AHJ is if or how the inside perimeter of the openings must be constructed. The UL assemblies do not address any openings within the tested assemblies. What is this boards opinion. Do the jambs, sill and head of the bearing wall openings need to be wrapped with the same rated drywall at the wall facings or because the openings can be unprotected is this not required.

If the opinion is that it is required can the perimeter framing be protected by equivalent means other than drywall such as intumescent coating or equivalent rating of cement board, etc.

This involves some new projects as well as one under construction so we are looking for options that are still code compliant.
 
Funny... I am dealing with this exact same issue on an over/under duplex. I asked the chief inspector about it, and he didn't understand the question... just said the openings were unlimited (this is a problem with email conversations... so much lost in translation).

It seems like we would need to wrap the openings with drywall, and tape/float the joints... interior and exterior walls alike.

I am very interested in watching this thread... hopefully someone can answer this one ASAP.
 
I am betting it is R302.3.1.

Jack is right, though... no mention of how to resolve the openings in said assemblies.

Code books need photos or illustrations.
 
How can the structure be rated if the openings are not?

Any openings in rated assemblies get rated accordingly. Chapter 7, immediately after the assemblies there is a section on opening protectives.
 
EnvisionMan said:
I am betting it is R302.3.1.Jack is right, though... no mention of how to resolve the openings in said assemblies.

Code books need photos or illustrations.
Click to expand...
Well if you are using 2009 or 2012

R302.3 Two-family dwellings. Dwelling units in two-family dwellings shall be separated from each other by wall and/or floor assemblies having not less than a 1-hour fire-resistance rating when tested in accordance with ASTM E 119 or UL 263. Fire-resistance-rated floor-ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.

Exceptions:

1. A fire-resistance rating of 1/2 hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with NFPA 13.

2. Wall assemblies need not extend through attic spaces when the ceiling is protected by not less than 5/8-inch (15.9 mm) Type X gypsum board and an attic draft stop constructed as specified in Section R302.12.1 is provided above and along the wall assembly separating the dwellings. The structural framing supporting the ceiling shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent.

R302.3.1 Supporting construction. When floor assemblies are required to be fire-resistance rated by Section R302.3, the supporting construction of such assemblies shall have an equal or greater fire-resistance rating.
 
If the above section, you cannot have an unprotected opening.

Do you want to pick another section??
 
We have this issue on several projects. One is R-2 and others are I-1 and I-2. The issue is that IBC 2009 or any code for that matter does not clarify what is specifically meant by protection of structure when it comes to a bearing wall that is a series of bearing members. It address individual members such as columns which usually occur in different conditions. We use wood stud and metal stud bearing walls, including systems such as Infinity which reflect a UL Design assembly that does not address openings and how the tested assembly works with unprotected openings. We all know that the same wall with a rated window or door opening is acceptable, but I can find nothing in the UL Directory, IBC or NFPA which clarifies the condition we are discussing. For future projects we will probably proceed with the most stringent detail, but I am trying to work with a field condition that could be problematic and am looking for information to help solve the issue with the least cost and inconvenience to the project.

Thanks.
 
jackbweth said:
We have this issue on several projects. One is R-2 and others are I-1 and I-2. The issue is that IBC 2009 or any code for that matter does not clarify what is specifically meant by protection of structure when it comes to a bearing wall that is a series of bearing members. It address individual members such as columns which usually occur in different conditions. We use wood stud and metal stud bearing walls, including systems such as Infinity which reflect a UL Design assembly that does not address openings and how the tested assembly works with unprotected openings. We all know that the same wall with a rated window or door opening is acceptable, but I can find nothing in the UL Directory, IBC or NFPA which clarifies the condition we are discussing. For future projects we will probably proceed with the most stringent detail, but I am trying to work with a field condition that could be problematic and am looking for information to help solve the issue with the least cost and inconvenience to the project.Thanks.
Click to expand...
just asking for a code section where the walls are requried

This will help answer the question, if it is a wall between units, no opening allowed

it it is an exterior wall, than possible an unprotected opening is allowed

If it is a wall with in a unit such as say going into a bedroom, than sounds like you need to wrap the opening to maintain the rating..

CODE sections help no where you are trying to go, general questions are sometimes hard to answer, to many variables.
 
IBC 2009, 704.3 and 704.4 address this issue as well as 705.5 and 705.6 for exterior walls which is the condition we have most often. the code in 704.10 states that need for complete protection (4 sided) for columns to avoid a catastrophic failure, but in a bearing wall with multiple members failure of one member would not cause such a failure. Many times in an opening the bearing stud is not next to the opening, but just a blocking member. The combination of the non bearing stud, blocking, the window or door frame, etc. also provides some resistance and protection to the adjacent framing members.

My point is that the UL design should have incorporated an opening in the tested assembly so that the detail of how to frame and protect the structural members was clear. By totally ignoring a very standard condition of an exterior wall we in the industry are left to our own or AHJ interpretations.
 
Table 601 - Bearing Walls is the code section that requires rated bearing walls for Type 1, 2, 3 and 5 construction which applies to most projects. This requirement does not require fire resistance ratings to separate spaces, functions or occupancies, but requires the rating for protection of structure only and other sections address the compliance requirements for the unprotected openings. We have conditions which permit unprotected openings so the only issue is what detail constitutes protection of the structure at the opening.
 
"My point is that the UL design should have incorporated an opening in the tested assembly so that the detail of how to frame and protect the structural members was clear."

Have you ever seen a UL vert or horiz assembly that also gave termination details? Or intersection details? They just don't do it.....
 
steveray: You are right that UL does not provide all the information on their assemblies. but head of wall and intersecting details are available for third party sources such as Hilti, USG, etc and these manufacturers will also provide engineering judgments to assist in unusual conditions. AHJ's will accept this information to supplement the UL design. An unprotected opening for structural protection seems like a common sense condition to test in an exterior wall since it is a situation guaranteed to occur. I realize logic doesn't apply to these things, but surely this issue has occurred many times before and you would at least think that IBC would have made an interpretation. We have also spoken with IBC and even they don't have complete agreement between the people we spoke with.
 
You need to be looking at the beam ratings for the header over the opening not the wall ratings.

For one hour the wood door frame and jack studs are probably sufficient protection.

For 2 hour lightweight construction may need a rated door frame.
 
Thanks Frank - that's what we thought, but we just got off the phone with ICC and they are referencing 704.4.1 and advising that the entire non protected opening must be wrapped with the same protected membrane assembly as the wall for both interior and exterior walls. This causes a problem with exterior walls because we don't permit drywall to be installed until the building is dried in. The reviewer readily admitted that this has not been an issue and most AHJ's have accepted the standard construction as substantially meeting the intent, but if a technical interpretation was to be made the framing members of a load bearing wall would all be protected at opening the same as the interior wall surface.

I know there are thousands of buildings built that do not incorporate this detail and have never heard of a fire related failure due to this issue.
 
"This causes a problem with exterior walls because we don't permit drywall to be installed until the building is dried in."

How do they sheath with DensGlass there? Do they have to tent it?
 
We don't permit interior drywall to be installed until the sheathing and windows are in place. We may have to wrap the openings with Densglass and will still get questioned because it varies slightly from the UL design. It's getting to be analysis paralysis mode with so much scrutiny and overthinking at times. All our buildings are sprinkled, most are non-combustible and are probably some of the safest buildings constructed, but that's the way things are going.
 
Is the load bearing header directly above the window?

Or can you separate it from the window with wood and insulation?

One layer 5/8 Type X is 40 minutes. 2x? wood framing is 20 minutes. Insulating the wall gives an additional 15 minutes. An inch of wood is 20 minutes. Therefore separating the wood beam from the window opening with 1-1/2 inch of wood for one hour wall or 3 inches for 2 hour wall (or oversizing the beam) gives equivalent protection. The Section 721 Calculated method does not mention the need to provide protection of the opening.

Reference Section 721.6 2009 IBC.
 
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