# Truss System - Center Load Bearing Walls?



## cortell (Nov 27, 2010)

If all the trusses are identical, I would look for a large area where the trusses aren't supported by a wall along that same line (or near it). For example, does that wall just stop and then the area past it (along the same path) become a big open living room with no bulkead or beam in sight? If so, then that tells me those trusses aren't relying on the kitchen wall. If they are, what's holding them up in the living room (assuming remodeling hasn't happened in that home)? If there's another wall somewhere nearby, the situation becomes murky

Couple things about this approach. It heavily depends on
1. again, all the trusses being *identical* in spacing, configuration and in span. 
2. the area above the walled section and the unwalled section have equal load (there's no, e.g., water heater above the walled area

That said, i'm not a structural engineer and I don't recommend you making the call if you're not experienced enough to accurately identify a load bearing wall.


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## aggiesrok (May 7, 2009)

cortell said:


> If all the trusses are identical, I would look for a large area where the trusses aren't supported by a wall along that same line (or near it). For example, does that wall just stop and then the area past it (along the same path) become a big open living room with no bulkead or beam in sight? If so, then that tells me those trusses aren't relying on the kitchen wall. If they are, what's holding them up in the living room (assuming remodeling hasn't happened in that home)? If there's another wall somewhere nearby, the situation becomes murky
> 
> Couple things about this approach. It heavily depends on
> 1. again, all the trusses being *identical* in spacing, configuration and in span.
> ...


They seem to be identical, they extend beyond the kitchen exterior wall and include the covered front porch, I can see the soffitt vents at the end. The kitchen wall is about 16' across with about a 5' opening between the LV and Kit (framed like bulkhead, but not sure if it has a header across), then where the kit wall ends there is a 7' span across the foyer with no bulkhead.


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## Daniel Holzman (Mar 10, 2009)

Unfortunately this question is not as simple as it appears. The truss could have been designed to span 30 feet, and it is possible that the center wall does not contact the truss, hence provides no support. If that is the case, then removing the center wall would not affect the truss, but could affect the lateral stability of the house under high wind conditions.

It is also possible that the truss was not designed to span 30 feet, and relies on the center wall to reduce the effective span to 15 feet. In this case, the wall would be hard up against the trusses. However, note that even if the walls are hard against the trusses, this does not guarantee that the trusses are unable to span 30 feet, but it would raise other issues.

The best way to go about analyzing the question is to measure the gap, if any, between the wall and the truss. If there is a gap between the top of wall and each truss, then clearly the wall is not load bearing, and you need only evaluate the contribution of the center wall to lateral stability of the house, which is something an engineer can do for you. On the other hand, if the wall is actually touching the trusses, you need to contact the truss manufacturer, whose name may be stamped on each truss, to determine if the particular truss you have is designed to span 30 feet, or relies on an intermediate support.

There is another complexity here you need to be aware of. If the truss is designed to span 30 feet, but is being held up at the midpoint by the wall, removal of the wall is likely to lead to deflection of the truss at the midpoint, which can lead to cracking of the ceiling drywall. The truss manufacturer may be able to estimate the additional deflection the truss will undergo if a center support is removed. If they cannot or will not do the computations, you are going to need an engineer to analyze the matter, since truss deflection is not a simple analysis.


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## cortell (Nov 27, 2010)

aggiesrok said:


> They seem to be identical, they extend beyond the kitchen exterior wall and include the covered front porch, I can see the soffitt vents at the end. The kitchen wall is about 16' across with about a 5' opening between the LV and Kit (framed like bulkhead, but not sure if it has a header across), then where the kit wall ends there is a 7' span across the foyer with no bulkhead.


Hm. That bulkhead thickens the plot. If there's a header in there, then that tells me with with almost certainty it's a load bearing wall. It could, however, be running utility lines or even be there for decorative reasons. Personally, I would carefully make an opening in it to find out for sure.

The 7' span across the foyer, though, is encouraging. If the trusses are identical over that area, and there's no additional loads over the kitchen area, that is a strong clue, IMO, that the kitchen wall isn't load bearing. 

Again, though, I absolutely would not rely on someone's guess work over the internet--which is what my input is. Making a good determination requires examining the situation thoroughly, something that can't be done with descriptions and a few pics. If you were to take video of the attic and your downstrairs, post it on youtube and provide a link here, you may be able to solicit more reliable opinions.


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## aggiesrok (May 7, 2009)

Thanks for the assistance. Like I said I am buying, but the home inspection is next week and hopefully he can shed some light. I was hopeful when I saw the trusses. After closing, I will remove the sheetrock around the bulkhead to see about a header. Although I guess it's possible to have a header through habit of framers and not need it.


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## cortell (Nov 27, 2010)

aggiesrok said:


> Thanks for the assistance. Like I said I am buying, but the home inspection is next week and hopefully he can shed some light. I was hopeful when I saw the trusses. After closing, I will remove the sheetrock around the bulkhead to see about a header. Although I guess it's possible to have a header through habit of framers and not need it.


If that wall is original (not added or touched through a remodel), and the house was built with engineered drawings, I wouldn't consider that a possibility. Headers are specified in the plans. The likelihood a carpenter would slow his progress by putting a header where it wasn't needed and specified seems very unlikely to me. If that was an original wall and I found a header in that bulkhead, that would put the issue to rest for me--I wouldn't remove the wall.

The other possibility, mentioned by Daniel, is that the wall does nothing for the roof but still has a structural role. It could be a braced wall panel. If there's only sheetrock attached to the studs (both sides) and there's no let-in bracing, then it's near certain it's not providing that structural role, either.
An interior braced wall is common if the house is an elongated rectangle (length to width ratio exceeds 3:1).


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## aggiesrok (May 7, 2009)

If it is load bearing, I'll just take the wall out to the corner and put up a header, In this case, it would be a 14' opening and just keep a bulkhead there. There was a piece of paper stapled to the truss at the top of the attic stairs. It was a little chewed up looking and didn't read it, hopefully that has some info on the trusses.


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## Gary in WA (Mar 11, 2009)

Could we get a picture of the other side of center post in attic? And one directly over the wall in question?

cortell, you'll enjoy this- Table 4, gyp alone on wall is better than wood diagonal braced wall without gyp, and same as metal strapped wall before 3/8" deflection. Of course, taping the joints, panel orientation, and fastener connection all have an influence on its racking strength. http://www.fpl.fs.fed.us/documnts/fplrp/fplrp439.pdf
Around here, in our seismic zone, we have a lot of interior drywalled (only) shear walls, and many plywood/OSB paneled ones. You should see our foundation/wall hold-downs.....lol.Take stock in Simpson everyone.

Gary


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## cortell (Nov 27, 2010)

GBR in WA said:


> cortell, you'll enjoy this- Table 4, gyp alone on wall is better than wood diagonal braced wall without gyp, and same as metal strapped wall before 3/8" deflection. Of course, taping the joints, panel orientation, and fastener connection all have an influence on its racking strength. http://www.fpl.fs.fed.us/documnts/fplrp/fplrp439.pdf
> Around here, in our seismic zone, we have a lot of interior drywalled (only) shear walls, and many plywood/OSB paneled ones. You should see our foundation/wall hold-downs.....lol.Take stock in Simpson everyone.


Jeesh. I never would have believed it had I not seen it. Thanks. But, just to be clear--a wall with only sheetrock does not count as a shear wall, right? I'm not crazy there, am I? Add 1x4 let-in bracing or strap, and you have a shear wall, right? Hm...or are you hinting that a wall with drywall on _both _sides does in fact count as a shear wall?


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## cortell (Nov 27, 2010)

cortell said:


> Hm...or are you hinting that a wall with drywall on _both _sides does in fact count as a shear wall?


Gary, I missed part of your comment that answers this. Though if I have this right, it seems to me that drywall installed with standard drywall nails or screws would probably not make the wall a shear wall. 

I learn something new every day on this forum, thanks to people like you and Daniel who keep us DIYers in check.


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## Gary in WA (Mar 11, 2009)

Daniel nailed it. I have had to install drywall (both sides on a long wall to get the shear) where the SE called out for it- in the house center. Drywall alone is minimally structural due to warp and breakage compared to the new "T" bars. And the alternate minimal shear to meet code are rated much below ply panels required for exterior walls: http://bct.eco.umass.edu/publications/by-title/insulating-on-the-outside/

On ceilings for shear resistance, note footnote "a" and "b"; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_7_sec002_par012.htm

In the OP's case, the drywall may be helping hold the gable-end wall in check- removing a section may require an engineer's help- especially if in a seismic or high wind area, as Daniel said. I've had the OSB one side of both remaining sections per SE.

The later trusses have a red colored paper or sticker on the bearing-point-load to avoid confusion. Though I have installed many trusses (bearing walls below) with no markings years ago. Pictures would help...

Gary


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## Joe Carola (Apr 14, 2006)

aggiesrok said:


> Like I said I am buying, but the home inspection is next week and hopefully he can shed some light. .


Home inspectors are not qualified to answer these questions. They are not engineers.


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## tony.g (Apr 15, 2012)

cortell said:


> I learn something new every day on this forum, thanks to people like you and Daniel who keep us DIYers in check.


I should like to second that, and to thank GBR for the reference on gyypsum wallboard. The next time a local authority building inspector asks for a stud wall to be diaphragmed with plywood /OSB, I shall be prepared!:wink:.


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