IRC Section R602.7 Headers, Table R602.7(1)

[YNWA2023]

Does Table R602.7(1) take into account whether the exterior bearing wall is on eave side or gable side? It doesn't seem to distinguish clearly, except the small pictorial images indicate that the wall in consideration is on the eave side. But no verbiage to support this. BUT the width in this chart is defined as measured perpendicular to the roof ridge (footnote C). If the building width is defined as such and is a factor to determine the header size, then this chart should be unique to the loadbearing walls, in this case, the exterior walls on eave side that support floor joists and roof trusses....because obviously, longer the span (the building width), more robust the header needs to be on the wall receiving the load of floor and roof.

I had a whole another discussion (on Reddit) how the the gable side wall is not recognized as nonbearing wall by the IRC definition. I understand this by the definition, but in practice and theory, the gable side wall is not bearing as much load as the walls supporting the ends of joists and trusses. (They are however important to resist lateral loads, hence they act as braced wall. But that's another discussion.)

It doesn't make sense to me that the table R602.7(1) is a catch all scenarios, applying to all sides of exterior walls.

Is there another chart that I can reference to determine the size of the headers that go into gable side walls?

 

[Yankee Chronicler]

I suggest you review this discussion: https://www.thebuildingcodeforum.co...minology-for-non-bearing-exterior-wall.36015/

I had a whole another discussion (on Reddit) how the the gable side wall is not recognized as nonbearing wall by the IRC definition.

I disagree.

 

[wwhitney]

I had a whole another discussion (on Reddit) how the the gable side wall is not recognized as nonbearing wall by the IRC definition.

How's that? If all the joists and rafters bear only on the eave walls, then the gable side wall meets the definition of non-load bearing in the IRC. In which R602.7.4 applies.

Cheers, Wayne

 

[wwhitney]

I suggest you review this discussion: https://www.thebuildingcodeforum.co...minology-for-non-bearing-exterior-wall.36015/

Note that the definitions in the IRC and IBC differ. The IRC definition does not have an exclusion for wood framed walls that support less "than 100 pounds per linear foot of vertical load."

Cheers, Wayne

 

[Yankee Chronicler]

Note that the definitions in the IRC and IBC differ. The IRC definition does not have an exclusion for wood framed walls that support less "than 100 pounds per linear foot of vertical load."

Cheers, Wayne

Got me again. Unfortunately, I mostly live in the IBC. It bugs me no end when the ICC can't use the same terms consistently from one book to another.

Nonetheless, the IRC definition does hinge on vertical loads in addition to the wall's own weight. So wind loads and forces imposed by racking of braced wall panels aren't a consideration..

 

[Mr. Inspector]

The IRC tables are a catch all made for the worst-case scenario. There would be a whole need for more tables depending on if the ceiling joists are supporting on the gable end of none or multiple floors or a mezzanine, the truss design (most of the time I see vertical studs 16" or 24" o. c. coming down on the gable end truss in our area), if floor joists or trusses are zero or up to 3 floors are supported or partly supported on the gable end and if they are for living or sleeping areas, hip roofs, A frames and other odd shaped roofs, large overhangs, if the gable end is also supporting a balcony, deck, porch roof or both, large heavy windows. An engineer can decide to not go by the tables.

Notice the foundation requirements are not different for the gable ends too.

 

[YNWA2023]

I suggest you review this discussion: https://www.thebuildingcodeforum.co...minology-for-non-bearing-exterior-wall.36015/



I disagree.

Someone else might have pointed out.. But IRC and IBC define a load-bearing wall differently, and for my project (an alteration to a detached single family home), IRC prevails. Load-bearing wall. A wall supporting any vertical load in addition to its own weight. Any vertical load would push the wall to become load-bearing.

 

[mtlogcabin]

Gable End Bracing | Structural Building Components Association

sbcindustry.com

Manufactured gable ends are actually frames even though they are often referred to as trusses. The webs are “studs” oriented vertically and usually spaced at 12, 16 or 24 in. O.C. The gable end frame is designed to transfer vertical loads from the roof to the continuous bearing wall below.

R602.7.4 Nonbearing walls.
Load-bearing headers are not required in interior or exterior nonbearing walls. A single flat 2-inch by 4-inch (51 mm by 102 mm) member shall be permitted to be used as a header in interior or exterior nonbearing walls for openings up to 8 feet (2438 mm) in width if the vertical distance to the parallel nailing surface above is not more than 24 inches (610 mm). For such nonbearing headers, cripples or blocking are not required above the header.

 

[YNWA2023]

How's that? If all the joists and rafters bear only on the eave walls, then the gable side wall meets the definition of non-load bearing in the IRC. In which R602.7.4 applies.

Cheers, Wayne

IRC Definition Load-bearing wall. A wall supporting any vertical load in addition to its own weight.

I should have given more contexts to my original post. I am designing new window openings to the first floor of the gable side wall. There is a second floor and roof over it. The wall is bearing some load, even though the load is much less than the eave side. Perhaps the second floor wall would be considered nonbearing.

 

[YNWA2023]

R602.7.4 Nonbearing walls.
Load-bearing headers are not required in interior or exterior nonbearing walls. A single flat 2-inch by 4-inch (51 mm by 102 mm) member shall be permitted to be used as a header in interior or exterior nonbearing walls for openings up to 8 feet (2438 mm) in width if the vertical distance to the parallel nailing surface above is not more than 24 inches (610 mm). For such nonbearing headers, cripples or blocking are not required above the header.

This code section cannot be applied to my design, so I am told by the plan reviewer. Because the wall is on the first floor, it does carry some load even on the gable side.

 

[wwhitney]

I should have given more contexts to my original post. I am designing new window openings to the first floor of the gable side wall. There is a second floor and roof over it. The wall is bearing some load, even though the load is much less than the eave side.

Can you clarify what load it is carrying besides self load? What structure outside of the wall would collapse if the whole gable wall were removed, without removing those members that are repeated outside the wall, like floor joists and rafters? If the answer is none, perhaps you could explain to your plan reviewer that makes the gable end wall nonbearing.

Of course, that raises the question of the situation where all the building elements parallel to the wall are sized to suffice without the wall present, but because the wall is there, they will incidentally bear on the wall, and whether that makes the wall load bearing or not.

As to Table R602.7(1), building width should be understood to be twice the tributary length. So if you gable wall for some reason has a tributary length of a couple feet perpendicular to it, you could use the 12' building width column in that table.

Cheers, Wayne

 

[bill1952]

So, some gable walls are load bearing and some are non-load bearing. Sort of like all walls. Depends how they are designed and built. Hard to speculate without a sketch and saying treat it as load bearing is safe.

Both my old house were sheathed with 1x12 rough sawn pine horizontally and had no headers anywhere what so ever. The just cut a hole and installed a window, most for a 46" rough opening width so just looped off 2 studs. Balloon frame so the sheathing was carrying second floor loads. Well past 100 years they were fine. Confused me first time I learned how it was built.

 

[Joe.B]

I mostly live in the IBC. It bugs me no end when the ICC can't use the same terms consistently from one book to another.

If I understand correctly the IBC and IRC have different origins. In California they didn't have a Residential code until 2010, based off of the 2009 IRC. Before that the last adopted CA Building Code was 2001 and was based off of the 1997 Uniform Building Code. The 2009 IBC looks an awful lot like the 1997 UBC, including the definition for "Bearing Wall". I would postulate that the IBC was heavily influenced by the UBC, and the Residential Code comes from somewhere else entirely, CABO in the 70's?

 

[Yankee Chronicler]

This code section cannot be applied to my design, so I am told by the plan reviewer. Because the wall is on the first floor, it does carry some load even on the gable side.

What load does it carry -- besides it's own weight? Is he saying the first floor "bears" the second floor? What if the gable end walls were balloon framed?